Speed up String#blank? Regex

Follow up on https://github.com/rails/rails/commit/697384df36a939e565b7c08725017d49dc83fe40#commitcomment-17184696.

The regex to detect a blank string `/\A[[:space:]]*\z/` will loop through every character in the string to ensure that all of them are a `:space:` type. We can invert this logic and instead look for any non-`:space:` characters. When that happens, we would return on the first character found and the regex engine does not need to keep looking.

Thanks @nellshamrell for the regex talk at LSRC.

By defining a "blank" string as any string that does not have a non-whitespace character (yes, double negative) we can get a substantial speed bump.

Also an inline regex is (barely) faster than a regex in a constant, since it skips the constant lookup. A regex literal is frozen by default.

```ruby
require 'benchmark/ips'

def string_generate
  str = " abcdefghijklmnopqrstuvwxyz\t".freeze
  str[rand(0..(str.length - 1))] * rand(0..23)
end

strings = 100.times.map { string_generate }

ALL_WHITESPACE_STAR = /\A[[:space:]]*\z/

Benchmark.ips do |x|
  x.report('current regex            ') { strings.each {|str| str.empty? || ALL_WHITESPACE_STAR === str } }
  x.report('+ instead of *           ') { strings.each {|str| str.empty? || /\A[[:space:]]+\z/ === str } }
  x.report('not a non-whitespace char') { strings.each {|str| str.empty? || !(/[[:^space:]]/ === str) } }
  x.compare!
end

# Warming up --------------------------------------
# current regex
#                          1.744k i/100ms
# not a non-whitespace char
#                          2.264k i/100ms
# Calculating -------------------------------------
# current regex
#                          18.078k (± 8.9%) i/s -     90.688k
# not a non-whitespace char
#                          23.580k (± 7.1%) i/s -    117.728k

# Comparison:
# not a non-whitespace char:    23580.3 i/s
# current regex            :    18078.2 i/s - 1.30x slower
```

This makes the method roughly 30% faster `(23.580 - 18.078)/18.078 * 100`.

cc/ @fxn

create_join_table should work with uuid

Use of `whether or not` instead of `regardless if ... or not`

Dump indexes in `create_table` for generates SQL in one query

See the rationale in the comment in this patch.

To benchmark this I ran a number of variations, ultimately narrowing to

    require 'benchmark/ips'

    str = ''
    regexp = /\A[[:space:]]*\z/

    Benchmark.ips do |x|
      x.report('regexp') { regexp === str }
      x.report('empty')  { str.empty? || regexp === str }
      x.compare!
    end

This benchmark has consistently reported speedups around 3.5x:

    Calculating -------------------------------------
                  regexp    69.197k i/100ms
                   empty   115.468k i/100ms
    -------------------------------------------------
                  regexp      2. 6.3%) i/s -     13.839M
                   empty      9. 8.8%) i/s -     47.804M

    Comparison:
                   empty:  9642607.6 i/s
                  regexp:  2768351.9 i/s - 3.48x slower

Sometimes even reaching 4x.

Running the same bechmark on strings of 10 or 100 characters (with
whitespace or present) has shown a slowdown of just about 1.01/1.02.
Marginal, we seem to have a worthwhile trade-off here.

use rails command in `time:zones` task desc [ci skip]

Fix example for css_class_attribute and fix indentation

[ci skip] Small grammar fix

Add ActiveSupport::TimeZone.country_zones helper

date_select helper with_css_classes option also accept a hash

[ci skip]

Add html_safe support to ActionView Array#OutputSafetyHelper

Object#inspect recursively inspects instance variables, exposing all
internal state, including sensitive internal cache objects. Override
Cache#inspect to give a high-level summary that never interferes with
concurrent cache writes.

If the adapter supports indexes in create table, it generates SQL
in one query.

Fix `test_blank_columns_created_in_block`

Follow up to 1683410c.

Do not destructively mutate passed options hash in route definitions

remove rails 4 specification in bin/rails for plugins [ci skip]

Remove unecessary comment

Added documentation for ActiveJob queue adapter for a specific job. [ci skip]

[ci skip] Added note on child class maintaining parent's queue adapter.

[ci skip] Added note on child class maintaining parent's queue adapter.

[ci skip] removed documentation for child class inheriting the queue adapter.

That helper will return time zones for any country that tzdata knows about.
So it will be much simpler for non-US people to list own country time zones
in HTML selects or anywhere.

Define `arel_visitor` method on all adapters

`Arel::Visitors::VISITORS` was removed at https://github.com/rails/arel/pull/412.

Small typo on a method name:

Remove reference to unknown method `dirty?` in docs [ci skip]

[ci skip]

Update send_data documentation [ci skip]

Add missing period after sentence.

Change the Hash.to_xml with a lamda example