Add minSdkVersion to default manifests

If the default manifest that doesn't set minSdkVersion is passed to
manifest merger along with a library manifest that does, it will fail
with:
.../DefaultManifest.xml Error:
	uses-sdk:minSdkVersion 1 cannot be smaller than version 14 declared in library ...

Translate LOCAL_MIN_SDK_VERSION or LOCAL_SDK_VERSION to minSdkVersion
in DefaultManifest.xml.

Bug: 79481102
Test: m checkbuild
Change-Id: I4d792d48612e6a1111e05a9e4a71bb4d87eae1ad