Add some missing `LLVM::Context` bindings #11396

Job	Run time
deploy_api_docs	0s
check_format	1m 54s
x86_64-gnu-test (1.7.3)	32m 25s
x86_64-gnu-test-preview_mt	5m 47s
x86_64-gnu-test (1.8.2)	34m 11s
x86_64-gnu-test (1.9.2)	32m 42s
x86_64-musl-test	38m 55s
x86_64-gnu-test (1.10.1)	33m 40s
x86_64-gnu-test (1.11.2)	32m 31s
x86_64-gnu-test (1.12.1)	34m 22s
x86_64-gnu-test (1.0.0, FLAGS=-Dwithout_ffi USE_PCRE1=true)	32m 45s
x86_64-gnu-test (1.1.1, FLAGS=-Dwithout_ffi USE_PCRE1=true)	36m 2s
x86_64-gnu-test (1.2.2, USE_PCRE1=true)	35m 32s
x86_64-gnu-test (1.3.2, USE_PCRE1=true)	35m 29s
x86_64-gnu-test (1.4.1, USE_PCRE1=true)	34m 21s
x86_64-gnu-test (1.5.1, USE_PCRE1=true)	34m 44s
x86_64-gnu-test (1.6.2, USE_PCRE1=true)	34m 17s
	8h 9m 37s

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