frameworks/base: Set LOCAL_SDK_VERSION where possible.

This change sets LOCAL_SDK_VERSION for all packages where
this is possible without breaking the build, and
LOCAL_PRIVATE_PLATFORM_APIS := true otherwise.

Setting one of these two will be made required soon, and this
is a change in preparation for that. Not setting LOCAL_SDK_VERSION
makes the app implicitly depend on the bootclasspath, which is
often not required. This change effectively makes depending on
private apis opt-in rather than opt-out.

Test: make relevant packages
Bug: 73535841
Exempt-From-Owner-Approval: Global cleanup
Change-Id: I66b515d98d03264dbb893b7c55ba7bdddfb447a1
Merged-In: I26458e41ecb84de91ac9a356a5d4bafb44f463c1
Merged-In: I938efe7a2359302cbf4d5d6f786f963044e1bbbd
Merged-In: I72ce7f1c6242ddf9a5b36075761f3f1f1138cea1