Support jarjar sharding

- If the new option `jarjar_shards` is set, use this as the number
of shards and enable sharding.

- The plan is to use it on "big" jars such as framework-minus-apex, but
for now, we only use it in a "test" target,
`framework-minus-apex_jarjar-sharded`.

- Also add `framework-minus-apex_jarjar-sharded` to the various
hardcoded spacial cases.

Test: m framework-minus-apex framework-minus-apex_jarjar-sharded
  and make sure the javac output jars have the same entries.
  $ diff \
    <(jar tf $ANDROID_BUILD_TOP/out/soong/.intermediates/frameworks/base/framework-minus-apex/android_common/jarjar/framework.jar \
      | sort) \
    <(jar tf $ANDROID_BUILD_TOP/out/soong/.intermediates/frameworks/base/framework-minus-apex_jarjar-sharded/android_common/jarjar/framework-minus-apex_jarjar-sharded.jar \
      | sort)
  (no output)

Bug: 383559945
Flag: EXEMPT New options are not used on production jars
Change-Id: I94c2ad978add25267f22b65c063e9148901b208b