[Thread] add Thread aconfig_declaration to java_sdk_library

This commit also moves Thread flags to Connectivity/common to ease
maintenance.

Test: m framework-connectivity-t
Ignore-AOSP-First: cherry-pick of aosp/2971692
Bug: 317290555
Merged-In: I79be1b48058ce6fb08149e18cdd7a5f5b0762769
Change-Id: I8a71f4ee49cc68a9512f432e454469200f2a5058