Migrate apex/sdkextensions to packages/modules/SdkExtensions

BUG: 156286599
Test: TH and Forrest (mainline_modules)
Merged-In: I6f562fe5e01179c48c39cd72ff381fc800d0d14d
Change-Id: I0009d286205d7942c2d681936bfba38e074700d2
25 files changed