feat: unlock GVL for simple compression and decompression

[SpringMT]

Related to #79
In #79, GVL unlocking is limited to streaming only, so this PR unlocks GVL for simple compression and decompression.

This program demonstrates the difference:
(in benckmarks)

Simple Compression

$LOAD_PATH.unshift '../lib'
require 'zstd-ruby'
require 'thread'

GUESSES = (ENV['GUESSES'] || 1000).to_i
THREADS = (ENV['THREADS'] || 1).to_i

p GUESSES: GUESSES, THREADS: THREADS

sample_file_name = ARGV[0]
json_string = File.read("./samples/#{sample_file_name}")

queue = Queue.new
GUESSES.times { queue << json_string }
THREADS.times { queue << nil }
THREADS.times.map {
  Thread.new {
    while str = queue.pop
      Zstd.compress(json_string)
    end
  }
}.each(&:join)

Without this patch:

[springmt@MacBook-Pro] (main)✗ % time THREADS=4 bundle exec ruby multi_thread_comporess.rb city.json
{:GUESSES=>1000, :THREADS=>4}
THREADS=4 bundle exec ruby multi_thread_comporess.rb city.json  2.65s user 0.15s system 93% cpu 3.003 total

With the patch:

[springmt@MacBook-Pro] (main)✗ % time THREADS=4 bundle exec ruby multi_thread_comporess.rb city.json
{:GUESSES=>1000, :THREADS=>4}
THREADS=4 bundle exec ruby multi_thread_comporess.rb city.json  2.78s user 0.14s system 250% cpu 1.162 total

Simple Decompression

$LOAD_PATH.unshift '../lib'
require 'zstd-ruby'
require 'thread'

GUESSES = (ENV['GUESSES'] || 1000).to_i
THREADS = (ENV['THREADS'] || 1).to_i

p GUESSES: GUESSES, THREADS: THREADS

sample_file_name = ARGV[0]
json_string = File.read("./samples/#{sample_file_name}")
target = Zstd.compress(json_string)

queue = Queue.new
GUESSES.times { queue << target }
THREADS.times { queue << nil }
THREADS.times.map {
  Thread.new {
    while str = queue.pop
      Zstd.decompress(str)
    end
  }
}.each(&:join)

Without this patch:

[springmt@MacBook-Pro] (main)✗ % time THREADS=4 bundle exec ruby multi_thread_decomporess.rb city.json
{:GUESSES=>1000, :THREADS=>4}
THREADS=4 bundle exec ruby multi_thread_decomporess.rb city.json  0.98s user 0.17s system 86% cpu 1.323 total

With the patch:

[springmt@MacBook-Pro] (main)✗ % time THREADS=4 bundle exec ruby multi_thread_decomporess.rb city.json
{:GUESSES=>1000, :THREADS=>4}
THREADS=4 bundle exec ruby multi_thread_decomporess.rb city.json  1.03s user 0.17s system 180% cpu 0.666 total