Introduce JSON::Fragment #774

Job	Run time
Ruby memcheck	1m 1s
ruby-versions / Generate Ruby versions	4s
ubuntu-latest 2.7	1m 6s
ubuntu-latest 3.0	1m 4s
ubuntu-latest 3.1	37s
ubuntu-latest 3.2	37s
ubuntu-latest 3.3	40s
ubuntu-latest 3.4	1m 9s
ubuntu-latest head	1m 39s
ubuntu-latest jruby	1m 40s
ubuntu-latest jruby-head	1m 8s
macos-14 2.7	57s
macos-14 3.0	25s
macos-14 3.1	24s
macos-14 3.2	18s
macos-14 3.3	26s
macos-14 3.4	21s
macos-14 head	18s
macos-14 jruby	54s
macos-14 jruby-head	39s
windows-latest 2.7	4m 52s
windows-latest 3.0	3m 17s
windows-latest 3.1	3m 20s
windows-latest 3.2	2m 30s
windows-latest 3.3	4m 10s
windows-latest 3.4	4m 17s
windows-latest head	1m 45s
ubuntu-24.04-arm 3.4	50s
macos-13 3.4	35s
windows-latest mswin	2m 39s
ubuntu-latest jruby-9.4	1m 11s
macos-latest truffleruby-head	35s
ubuntu-latest truffleruby-head	2m 12s
	47m 40s

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