Move bootFrameworkProfileRule to platform_bootclasspath

Changes bootFrameworkProfileRule to use ModuleContext instead of
SingletonContext and moves the call from dexpreoptBootJar's
GenerateSingletonBuildActions method to platform_bootclasspath's
GenerateAndroidBuildActions.

Changing the context also allows the code to switch from
bootFrameworkProfileRule to GetGlobalSoongConfig.

Also extracts the shouldBuildBootImages function so it can be used by
platform_bootclasspath to preserve the existing behavior.

Bug: 177892522
Test: m droid
Change-Id: I30d3ca10be7f84348ad3aa9cc984dd15b8f6f4e9