Rewrite BigDecimal#sqrt in ruby using Integer.sqrt #398

Job	Run time
ruby-versions / Generate Ruby versions	3s
ubuntu-latest 2.7	1m 7s
ubuntu-latest 3.0	34s
ubuntu-latest 3.1	34s
ubuntu-latest 3.2	37s
ubuntu-latest 3.3	35s
ubuntu-latest 3.4	33s
ubuntu-latest debug	39s
ubuntu-latest head	27s
macos-latest 2.7	57s
macos-latest 3.0	24s
macos-latest 3.1	30s
macos-latest 3.2	26s
macos-latest 3.3	20s
macos-latest 3.4	22s
macos-latest debug	25s
macos-latest head	25s
macos-14 2.7	1m 0s
macos-14 3.0	26s
macos-14 3.1	35s
macos-14 3.2	38s
macos-14 3.3	23s
macos-14 3.4	22s
macos-14 debug	27s
macos-14 head	20s
windows-latest 2.7	3m 36s
windows-latest 3.3	2m 31s
windows-latest 3.4	2m 18s
windows-latest head	1m 57s
windows-latest mingw	1m 53s
windows-latest mswin	1m 23s
	26m 47s

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