Raise Assertion instead of RoutingError for routing assertion failures.

Before this change, assert_recognizes, assert_generates, and
assert_routing raised ActionController::RoutingError when they failed to
recognize the route.

This commit changes them to raise Assertion instead. This aligns with
convention for logical failures, and supports reporting tools that care
about the difference between logical failures and errors e.g. the
summary at the end of a test run.

- Fixes #5899

Show in log correct wrapped keys

[ci skip] closes #5790

Call undefine_attribute_methods only when defining new attributes

Make AC::LogSubscriber#send_file like #send_data

Fix a problem of translate_exception method in a Japanese (non English) environment.

Synchronize read and modification of @reserved_connections 

Don't use assert_block method. It will be removed.

Fixed DataMapper namings in symbols and constants.

Fix warning: shadowing outer local variable - constant.

Refactor define_restrict_dependency_method using reflection

Remove sort on attributes.keys

Make the method API more clear by explicitly showing the expected
arguments. This means that the options cannot be passed as second
argument because we are not relying on extract_options! anymore,
you are expected to give a selected key or `nil` if you want to pass
options, as it is the last argument.

Notice that this does not change the current method arguments contract
available in 3.2, it just brings back the same functionality with the
divider addition.

`class_attribute` already generates instance readers/writers by default,
so there's no need to add delegation methods.

Removes some "method redefined" warnings.

This reverts commit 23a98ffb.

[ci skip]

Minitest uses different signature for assert_no_match, so we have to
swap arguments.

The fix commited in e2a070cf was returning the `new_target`, as
a try to return whatever user replaced association with. The
problem is, the resulting association target may be ordered
differently. In such case we want to return the target that
will be later used for that association.