Previously it was the responsibility of the database tasks to translate
the invalid statement from creating a duplicate database into an
ActiveRecord::Tasks::DatabaseAlreadyExists error.

It's actually easier for us to do this detection inside of the adapter,
where we already do a case statement on the return code to translate the
error.

This commit introduces ActiveRecord::DatabaseAlreadyExists, a subclass
of StatementInvalid, and updates both AbstractMysqlAdapter and
PostgresqlAdapter to return this more specific exception in that case.

Because this is a subclass of the old exception, StatementInvalid, it
should be backwards compatible with any code expecting that from
create_database.

This works for both create_database and exectute("CREATE DATABASE")

Enabled matches_regex for MySql

Previously matches_regex was only availble on PostgreSql, this will enable it for MySql

Usage example:

    users = User.arel_table;
    users = User.arel_table; User.where(users[:email].matches_regexp('(.*)\@gmail.com'))

Update activerecord/test/cases/arel/visitors/mysql_test.rb
Co-Authored-By: NRyuta Kamizono <kamipo@gmail.com>

Documentation for ActionMailer's SMTP over SSL/TLS option

[ci skip]

Add missing bullet point to make clear this is
actually a separate option from
`:openssl_verify_mode`.

Add `:ssl/:tls`-option to guides as well [ci skip]

Remove redundant empty line when we don't use system test

This reverts commit e9651dee.

Now we're having both `=~` and `match?` for these objects, and it's nicer to have explicit tests for both of them

Add test case to guard the query count for relation cache (for #35982)

Applications are not supposed to use require_dependency in their own
code if running in zeitwerk mode, and require_dependency was initially
aliased to require with that use case in mind.

However, there are situations in which you cannot control the mode and
need to be compatible with both. There, you might need require_dependency
in case you are being executed in classic mode. Think about engines that
want to support both modes in their parent applications, for example.

Furthermore, Rails itself loads helpers using require_dependency.

Therefore, we need better compatibility.

```ruby
class String
  def to1(position)
    position = [position + length, -1].max if position < 0
    self[0, position + 1]
  end

  def to2(position)
    position += size if position < 0
    self[0, position + 1] || +""
  end
end

Benchmark.ips do |x|
  x.report("'foo'.to(1)")  { 'foo'.to(1) }
  x.report("'foo'.to1(1)") { 'foo'.to1(1) }
  x.report("'foo'.to2(1)") { 'foo'.to2(1) }

  x.report("'foo'.to(-1)")  { 'foo'.to(-1) }
  x.report("'foo'.to1(-1)") { 'foo'.to1(-1) }
  x.report("'foo'.to2(-1)") { 'foo'.to2(-1) }

  x.report("'foo'.to(-10)")  { 'foo'.to(-10) }
  x.report("'foo'.to1(-10)") { 'foo'.to1(-10) }
  x.report("'foo'.to2(-10)") { 'foo'.to2(-10) }
end
```

Result:

```
Warming up --------------------------------------
         'foo'.to(1)   199.859k i/100ms
        'foo'.to1(1)   220.293k i/100ms
        'foo'.to2(1)   221.522k i/100ms
        'foo'.to(-1)   205.032k i/100ms
       'foo'.to1(-1)   195.837k i/100ms
       'foo'.to2(-1)   214.975k i/100ms
       'foo'.to(-10)   214.331k i/100ms
      'foo'.to1(-10)   182.666k i/100ms
      'foo'.to2(-10)   224.696k i/100ms
Calculating -------------------------------------
         'foo'.to(1)      4.685M (± 4.2%) i/s -     23.583M in   5.042568s
        'foo'.to1(1)      5.233M (± 5.8%) i/s -     26.215M in   5.026778s
        'foo'.to2(1)      5.180M (± 5.7%) i/s -     25.918M in   5.020735s
        'foo'.to(-1)      4.253M (± 7.0%) i/s -     21.323M in   5.043133s
       'foo'.to1(-1)      4.438M (±11.2%) i/s -     21.934M in   5.025751s
       'foo'.to2(-1)      4.716M (± 9.8%) i/s -     23.432M in   5.028088s
       'foo'.to(-10)      4.678M (± 9.5%) i/s -     23.148M in   5.007379s
      'foo'.to1(-10)      4.428M (± 5.1%) i/s -     22.103M in   5.005155s
      'foo'.to2(-10)      5.243M (± 4.6%) i/s -     26.289M in   5.024695s
```

Use capture_sql helper method in tests

This reverts commit ac6f3c92, reversing
changes made to 5b0ea95a.

This is to guard the change in #35982

Improve String#first and #last performance

fix typo in actionpack CHANGELOG.md

HTML page save during screenshot and multiple shots per test

Allow specifying fixtures to be ignored in "_fixture" section

Use a smaller TIFF file as fixture

Allow specifying what fixtures can be ignored by setting
`ignore` in fixtures YAML file:

    # users.yml
    _fixture:
      ignore:
        - base

    base: &base
      admin: false
      introduction: "This is a default description"

    admin:
      <<: *base
      admin: true

    visitor:
      <<: *base

In the above example, "base" fixture will be ignored when creating
users fixture. This is helpful when you want to inherit attributes
and it makes your fixtures more "DRY".

To avoid a deprecation warning.

We're already running Performance/RegexpMatch cop, but it seems like the cop is not always =~ justice

It causes unexpected results when running tests in parallel.
Ref: https://buildkite.com/rails/rails/builds/62610#0165f6d9-b9c8-4948-9319-07b58bfbfd4f/989-998

Change test description with the correct URL name

Allow separate database env variables per-connection

This commit adds a feature which allows separate database ENV variables
to be defined for each spec in a 3-tier config. The names for the
environment variables will be `#{name.upcase}_DATABASE_URL`

This commit also introduces a change in behavior around handling of
`DATABASE_URL`. Instead of using `DATABASE_URL` to change _all_ specs
in a multi-database configuration, it will now only affect the `primary`
connection.