Implement SIP-61 `@unroll` annotation #32692

Job	Run time
test_non_bootstrapped	0s
test	32m 35s
test_scala2_library_tasty	0s
test_windows_fast	20m 31s
MiMa	12m 55s
community_build_a	49m 37s
community_build_b	55m 48s
test_windows_full	0s
community_build_c	46m 11s
test_java8	0s
test_sbt	15m 38s
build-msi-package	0s
build-sdk-package / build	8m 2s
build-chocolatey-package / build	17s
test-chocolatey-package	0s
publish_nightly	1s
publish_release	1s
nightly_documentation	1s
open_issue_on_failure	1s
	4h 1m 38s

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