Avoid opt_aset_with optimization inside multiple assignment

	Previously, since the opt_aset_with optimization was introduced,
	use of the opt_aset_with optimization inside multiple assignment
	would result in a segfault or incorrect instructions.

	Fixes [Bug #21012]

	Co-authored-by: Nobuyoshi Nakada <nobu.nakada@gmail.com>

[Feature #20205]

As a path toward enabling frozen string literals by default in the future,
this commit introduce "chilled strings". From a user perspective chilled
strings pretend to be frozen, but on the first attempt to mutate them,
they lose their frozen status and emit a warning rather than to raise a
`FrozenError`.

Implementation wise, `rb_compile_option_struct.frozen_string_literal` is
no longer a boolean but a tri-state of `enabled/disabled/unset`.

When code is compiled with frozen string literals neither explictly enabled
or disabled, string literals are compiled with a new `putchilledstring`
instruction. This instruction is identical to `putstring` except it marks
the String with the `STR_CHILLED (FL_USER3)` and `FL_FREEZE` flags.

Chilled strings have the `FL_FREEZE` flag as to minimize the need to check
for chilled strings across the codebase, and to improve compatibility with
C extensions.

Notes:
  - `String#freeze`: clears the chilled flag.
  - `String#-@`: acts as if the string was mutable.
  - `String#+@`: acts as if the string was mutable.
  - `String#clone`: copies the chilled flag.

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

In preparation for https://bugs.ruby-lang.org/issues/20205.

The `frozen_string_literal` compilation option will no longer
be a boolean but a tri-state: `on/off/default`.

Rather than exposing that an imemo has a flag and four fields, this
changes the implementation to only expose one field (the klass) and
fills the rest with 0. The type will have to fill in the values themselves.

Before this commit, we were mixing a lot of concerns with the prism
compile between RubyVM::InstructionSequence and the general entry
points to the prism parser/compiler.

This commit makes all of the various prism-related APIs mirror
their corresponding APIs in the existing parser/compiler. This means
we now have the correct frame naming, and it's much easier to follow
where the logic actually flows. Furthermore this consolidates a lot
of the prism initialization, making it easier to see where we could
potentially be raising errors.

When loading Ruby from a file, or parsing using
RubyVM::InstructionSequence.

xfree can handle null values, so we don't need to check it.

Introduce runtime flag for specifying the parser,

```
ruby --parser=prism
```

also update the description:

```
$ ruby --parser=prism --version
ruby 3.3.0dev (2023-12-08T04:47:14Z add-parser-runtime.. 0616384c9f) +PRISM [x86_64-darwin23]
```

[Bug #20044]

when the RUBY_FREE_ON_SHUTDOWN environment variable is set, manually free memory at shutdown.

Co-authored-by: Nobuyoshi Nakada <nobu@ruby-lang.org>
Co-authored-by: Peter Zhu <peter@peterzhu.ca>