Check if the argument is Thread::Backtrace::Location object

	[Bug #19262]
	---
	 ast.c                 | 5 +++++
	 test/ruby/test_ast.rb | 6 ++++++
	 2 files changed, 11 insertions(+)

Implementation for Language Server Protocol (LSP) sometimes needs token information.
For example both `m(1)` and `m(1, )` has same AST structure other than node locations
then it's impossible to check the existence of `,` from AST. However in later case,
it might be better to suggest variables list for the second argument.
Token information is important for such case.

This commit adds these methods.

* Add `keep_tokens` option for `RubyVM::AbstractSyntaxTree.parse`, `.parse_file` and `.of`
* Add `RubyVM::AbstractSyntaxTree::Node#tokens` which returns tokens for the node including tokens for descendants nodes.
* Add `RubyVM::AbstractSyntaxTree::Node#all_tokens` which returns all tokens for the input script regardless the receiver node.

[Feature #19070]

Impacts on memory usage and performance are below:

Memory usage:

```
$ cat test.rb
root = RubyVM::AbstractSyntaxTree.parse_file(File.expand_path('../test/ruby/test_keyword.rb', __FILE__), keep_tokens: true)

$ /usr/bin/time -f %Mkb /usr/local/bin/ruby -v
ruby 3.2.0dev (2022-11-19T09:41:54Z 19070-keep_tokens d3af1b8057) [x86_64-linux]
11408kb

# keep_tokens :false
$ /usr/bin/time -f %Mkb /usr/local/bin/ruby test.rb
17508kb

# keep_tokens :true
$ /usr/bin/time -f %Mkb /usr/local/bin/ruby test.rb
30960kb
```

Performance:

```
$ cat ../ast_keep_tokens.yml
prelude: |
  src = <<~SRC
    module M
      class C
        def m1(a, b)
          1 + a + b
        end
      end
    end
  SRC
benchmark:
  without_keep_tokens: |
    RubyVM::AbstractSyntaxTree.parse(src, keep_tokens: false)
  with_keep_tokens: |
    RubyVM::AbstractSyntaxTree.parse(src, keep_tokens: true)

$ make benchmark COMPARE_RUBY="./ruby" ARGS=../ast_keep_tokens.yml
/home/kaneko.y/.rbenv/shims/ruby --disable=gems -rrubygems -I../benchmark/lib ../benchmark/benchmark-driver/exe/benchmark-driver \
            --executables="compare-ruby::./ruby -I.ext/common --disable-gem" \
            --executables="built-ruby::./miniruby -I../lib -I. -I.ext/common  ../tool/runruby.rb --extout=.ext  -- --disable-gems --disable-gem" \
            --output=markdown --output-compare -v ../ast_keep_tokens.yml
compare-ruby: ruby 3.2.0dev (2022-11-19T09:41:54Z 19070-keep_tokens d3af1b8057) [x86_64-linux]
built-ruby: ruby 3.2.0dev (2022-11-19T09:41:54Z 19070-keep_tokens d3af1b8057) [x86_64-linux]
warming up..

|                     |compare-ruby|built-ruby|
|:--------------------|-----------:|---------:|
|without_keep_tokens  |     21.659k|   21.303k|
|                     |       1.02x|         -|
|with_keep_tokens     |      6.220k|    5.691k|
|                     |       1.09x|         -|
```

We want to use error highlight with eval'd code, specifically ERB
templates. We're able to recover the generated code for eval'd templates
and can get a parse tree for the ERB generated code, but we don't have a
way to get the node id from the backtrace location. So we can't pass the
right node into error highlight.

This patch gives us an API to get the node id from the backtrace
location so we can find the node in the AST.

Error Highlight PR: https://github.com/ruby/error_highlight/pull/26

Co-authored-by: Aaron Patterson <tenderlove@ruby-lang.org>

By this change, syntax error is recovered smaller units.
In the case below, "DEFN :bar" is same level with "CLASS :Foo"
now.

```
module Z
  class Foo
    foo.
  end

  def bar
  end
end
```

[Feature #19013]

If this option is enabled, SyntaxError is not raised and Node is
returned even if passed script is broken.

[Feature #19013]

Use ISEQ_BODY macro to get the rb_iseq_constant_body of the ISeq. Using
this macro will make it easier for us to change the allocation strategy
of rb_iseq_constant_body when using Variable Width Allocation.

[Bug #18434]

Now the following code works without an exception.

```
RubyVM.keep_script_lines = true

eval(<<END)
def foo
end
END

p RubyVM::AbstractSyntaxTree.of(method(:foo))
```

This check is needed to fix a bug of error_highlight when NameError
occurred in eval'ed code.
https://github.com/ruby/error_highlight/pull/16

The same check for proc/method has been already introduced since
64ac984129a7a4645efe5ac57c168ef880b479b2.

This `NODE` type was used in pre-YARV implementation, to improve
the performance of assignment to dynamic local variable defined at
the innermost scope.  It has no longer any actual difference with
`NODE_DASGN`, except for the node dump.