Remove internal deapexer module

The build ations will be created by the top-level apex.

Details
1. In GenerateAndroidBuildActions, do a graph walk to determine if the
   apex has exported deps.
2. If there are exported deps, call the newly introduced `deapex`
   function. This registers the build rules and returns a DeapexerInfo
object. This was previously provided by the internal deapexer
dependency.
3. Update `dexpreoptSystemServerJars and `provideApexExportsInfo` to use
   the DeapexerInfo object from (2).

A lot of unit tests that relied on the legacy mechanism of deapexing
have been updated.

Test: go test ./apex
Test: lunch cf_x86_64_phone-next-userdebug (uses mainline prebuilts)
Test: verified no diff in file_list.txt
Bug: 368337090
Change-Id: I0edb681beccac4d2a9ceb73f9a506c081a8a96e0