Add tests for the behavior of JSON.generate with base types subclasses #579

Job	Run time
Ruby memcheck	1m 4s
ruby-versions / Generate Ruby versions	3s
ubuntu-22.04 2.7	48s
ubuntu-22.04 3.0	36s
ubuntu-22.04 3.1	37s
ubuntu-22.04 3.2	26s
ubuntu-22.04 3.3	51s
ubuntu-22.04 head	1m 16s
ubuntu-22.04 jruby	1m 10s
ubuntu-22.04 jruby-head	51s
macos-13 2.7	1m 36s
macos-13 3.0	35s
macos-13 3.1	32s
macos-13 3.2	39s
macos-13 3.3	32s
macos-13 head	32s
macos-13 jruby	1m 24s
macos-13 jruby-head	1m 43s
macos-14 2.7	37s
macos-14 3.0	21s
macos-14 3.1	23s
macos-14 3.2	22s
macos-14 3.3	21s
macos-14 head	18s
macos-14 jruby	33s
macos-14 jruby-head	30s
windows-latest 2.7	4m 44s
windows-latest 3.0	2m 1s
windows-latest 3.1	2m 8s
windows-latest 3.2	3m 31s
windows-latest 3.3	3m 49s
windows-latest head	1m 31s
windows-latest mswin	1m 43s
ubuntu-latest jruby-9.4	45s
macos-latest truffleruby-head	30s
ubuntu-latest truffleruby-head	2m 9s
	41m 31s

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