Add release notes for v1.2.0 #8524

Job	Run time
unit-tests	6m 34s
jvm-tests-1	6m 35s
jvm-tests-2	6m 36s
jvm-tests-3	6m 35s
jvm-tests-4	6m 36s
generate-linux-launcher	6m 37s
generate-macos-launcher	6m 35s
generate-linux-arm64-native-launcher	0s
generate-macos-m1-launcher	0s
generate-mostly-static-launcher	6m 34s
generate-windows-launcher	6m 34s
bloop-memory-footprint	6m 33s
checks	6m 33s
docs-tests	6m 33s
format	17s
generate-static-launcher	6m 34s
reference-doc	1m 52s
test-hypothetical-sbt-export	25s
vc-redist	0s
native-macos-m1-tests	0s
native-mostly-static-tests-3	1s
native-mostly-static-tests-2	1s
native-mostly-static-tests-1	1s
native-mostly-static-tests-4	1s
publish	1s
native-windows-tests-1	1s
native-windows-tests-2	1s
native-windows-tests-3	1s
native-windows-tests-4	1s
native-static-tests-2	1s
native-static-tests-3	1s
native-static-tests-1	1s
native-static-tests-4	1s
native-linux-tests-1	1s
native-linux-tests-2	1s
native-linux-tests-3	1s
native-linux-tests-4	1s
native-macos-tests-2	1s
native-macos-tests-3	1s
native-macos-tests-1	1s
native-macos-tests-4	1s
launchers	1s
Update packages	1s
Update Windows packages	1s
	1h 28m 27s

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