[Bug #21440] Stop caching member list in frozen Data/Struct class

	Fix handling of PM_CONSTANT_PATH_NODE node in keyword arguments with ARGS_SPLAT

	This was handled correctly in parse.y (NODE_COLON2), but not in
	prism. This wasn't caught earlier, because I only added tests for
	the optimized case and not the unoptimized case. Add tests for
	the unoptimized case.

	In code terms:

	```ruby
	m(*a, kw: lvar::X)     # Does not require allocation for *a
	m(*a, kw: method()::X) # Requires allocation for *a
	```

	This commit fixes the second case when prism is used.

	[Bug #21380] Prohibit modification in String#split block

	Reported at https://hackerone.com/reports/3163876

This reverts commit acb19e8707093593e967b6af03d92da5c570ffc6.

	[Bug #20009] Support marshaling non-ASCII name class/module

	[Bug #21439] Fix `PM_SPLAT_NODE` compilation error in for loops (#13597)

	[Bug #21439] Fix PM_SPLAT_NODE compilation error in for loops

	This commit fixes a crash that occurred when using splat nodes (*) as
	the index variable in for loops. The error "Unexpected node type for
	index in for node: PM_SPLAT_NODE" was thrown because the compiler
	didn't know how to handle splat nodes in this context.

	The fix allows code like `for *x in [[1,2], [3,4]]` to compile and
	execute correctly, where the splat collects each sub-array.

	Fix memory leak in Prism's RubyVM::InstructionSequence.new

	[Bug #21394]

	There are two ways to make RubyVM::InstructionSequence.new raise which
	would cause the options->scopes to leak memory:

	1. Passing in any (non T_FILE) object where the to_str raises.
	2. Passing in a T_FILE object where String#initialize_dup raises. This is
	   because rb_io_path dups the string.

	Example 1:

	    10.times do
	      100_000.times do
	        RubyVM::InstructionSequence.new(nil)
	      rescue TypeError
	      end

	      puts `ps -o rss= -p #{$$}`
	    end

	Before:

	    13392
	    17104
	    20256
	    23920
	    27264
	    30432
	    33584
	    36752
	    40032
	    43232

	After:

	    9392
	    11072
	    11648
	    11648
	    11648
	    11712
	    11712
	    11712
	    11744
	    11744

	Example 2:

	    require "tempfile"

	    MyError = Class.new(StandardError)
	    String.prepend(Module.new do
	      def initialize_dup(_)
	        if $raise_on_dup
	          raise MyError
	        else
	          super
	        end
	      end
	    end)

	    Tempfile.create do |f|
	      10.times do
	        100_000.times do
	          $raise_on_dup = true
	          RubyVM::InstructionSequence.new(f)
	        rescue MyError
	        else
	          raise "MyError was not raised during RubyVM::InstructionSequence.new"
	        end

	        puts `ps -o rss= -p #{$$}`
	      ensure
	        $raise_on_dup = false
	      end
	    end

	Before:

	    14080
	    18512
	    22000
	    25184
	    28320
	    31600
	    34736
	    37904
	    41088
	    44256

	After:

	    12016
	    12464
	    12880
	    12880
	    12880
	    12912
	    12912
	    12912
	    12912
	    12912

	compile.c: Handle anonymous variables in `outer_variable_cmp`

	[Bug #21370]

	Fix memory leak with invalid yield in prism

	[Bug #21383]

	The following script leaks memory:

	    10.times do
	      20_000.times do
	        eval("class C; yield; end")
	      rescue SyntaxError
	      end

	      puts `ps -o rss= -p #{$$}`
	    end

	Before:

	    16464
	    25536
	    29424
	    35904
	    39552
	    44576
	    46736
	    51600
	    56096
	    59824

	After:

	    13488
	    16160
	    18240
	    20528
	    19760
	    21808
	    21680
	    22272
	    22064
	    22336

	[Bug #21357] Fix crash in Hash#merge with block

	Prior to https://github.com/ruby/ruby/commit/49b306ecb9e2e9e06e0b1590bacc5f4b38169c3c
	the `optional_arg` passed from `rb_hash_update_block_i` to `tbl_update`
	was a hash value (i.e. a VALUE). After that commit it changed to an
	`update_call_args`.

	If the block sets or changes the value, `tbl_update_modify` will set the
	`arg.value` back to an actual value and we won't crash. But in the case
	where the block returns the original value we end up calling
	`RB_OBJ_WRITTEN` with the `update_call_args` which is not expected and
	may crash.

	`arg.value` appears to only be used to pass to `RB_OBJ_WRITTEN` (others
	who need the `update_call_args` get it from `arg.arg`), so I don't think
	it needs to be set to anything upfront. And `tbl_update_modify` will set
	the `arg.value` in the cases we need the write barrier.