This provides a significant speedup for symbol, true, false,
nil, and 0-9, class/module, and a small speedup in most other cases.

Speedups (using included benchmarks):
:symbol        :: 60%
0-9            :: 50%
Class/Module   :: 50%
nil/true/false :: 20%
integer        :: 10%
[]             :: 10%
""             :: 3%

One reason this approach is faster is it reduces the number of
VM instructions for each interpolated value.

Initial idea, approach, and benchmarks from Eric Wong. I applied
the same approach against the master branch, updating it to handle
the significant internal changes since this was first proposed 4
years ago (such as CALL_INFO/CALL_CACHE -> CALL_DATA). I also
expanded it to optimize true/false/nil/0-9/class/module, and added
handling of missing methods, refined methods, and RUBY_DEBUG.

This renames the tostring insn to anytostring, and adds an
objtostring insn that implements the optimization. This requires
making a few functions non-static, and adding some non-static
functions.

This disables 4 YJIT tests.  Those tests should be reenabled after
YJIT optimizes the new objtostring insn.

Implements [Feature #13715]

Co-authored-by: Eric Wong <e@80x24.org>
Co-authored-by: Alan Wu <XrXr@users.noreply.github.com>
Co-authored-by: Yusuke Endoh <mame@ruby-lang.org>
Co-authored-by: Koichi Sasada <ko1@atdot.net>