Introduce JSON::Coder #713

Job	Run time
Ruby memcheck	1m 0s
ruby-versions / Generate Ruby versions	2s
ubuntu-22.04 2.7	55s
ubuntu-22.04 3.0	32s
ubuntu-22.04 3.1	37s
ubuntu-22.04 3.2	32s
ubuntu-22.04 3.3	34s
ubuntu-22.04 3.4	39s
ubuntu-22.04 head	1m 22s
ubuntu-22.04 jruby	48s
ubuntu-22.04 jruby-head	49s
macos-13 2.7	1m 35s
macos-13 3.0	43s
macos-13 3.1	35s
macos-13 3.2	42s
macos-13 3.3	38s
macos-13 3.4	37s
macos-13 head	30s
macos-13 jruby	55s
macos-13 jruby-head	53s
macos-14 2.7	55s
macos-14 3.0	20s
macos-14 3.1	29s
macos-14 3.2	17s
macos-14 3.3	18s
macos-14 3.4	25s
macos-14 head	18s
macos-14 jruby	38s
macos-14 jruby-head	41s
windows-latest 2.7	4m 27s
windows-latest 3.0	2m 34s
windows-latest 3.1	2m 37s
windows-latest 3.2	2m 16s
windows-latest 3.3	4m 7s
windows-latest 3.4	3m 22s
windows-latest head	2m 20s
windows-latest mswin	1m 51s
ubuntu-latest jruby-9.4	56s
macos-latest truffleruby-head	31s
ubuntu-latest truffleruby-head	1m 58s
	46m 18s

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