[Feature #19236]

In Ruby 3.3, `Hash.new` shall print a deprecation warning if keyword arguments
are passed instead of treating them as an implicit positional Hash.

This will allow to safely introduce a `capacity` keyword argument in 3.4

Co-authored-by: Jean Boussier <byroot@ruby-lang.org>

When `freeze: true` argument is passed.

[Bug #19427]

[Bug #19439]

The instance variables were restore on the Regexp source,
not the regexp itself.

Unfortunately we have a bit of a chicken and egg problem.

The source holds the encoding, and the encoding need to be set on
the source to be able to instantiate the Regexp.

So the instance variables have to be read on the `source`.
To correct this we transfert the instance variables after
instantiating the Regexp.

The only way to avoid this would be to read the instance variable
twice and rewind.

[Bug #19427]

The `proc` wouldn't be called either, that fixes both.