YJIT: Add specialized codegen function for TrueClass#===

[rwstauner]

TrueClass#=== is currently number 10 in the most frequent C calls list of the lobsters benchmark.

require "benchmark/ips"

def wrap
  true === true
  true === false
  true === :x
end

Benchmark.ips do |x|
  x.report(:wrap) do
    wrap
  end
end

before
Warming up --------------------------------------
                wrap     1.791M i/100ms
Calculating -------------------------------------
                wrap     17.806M (± 1.0%) i/s -     89.544M in   5.029363s

after
Warming up --------------------------------------
                wrap     4.024M i/100ms
Calculating -------------------------------------
                wrap     40.149M (± 1.1%) i/s -    201.223M in   5.012527s