Diff source dump and previous version dump for Cross-Version ABI Check

Created a function to determine the current finalization stage by
environment variable and the existence of a version folder
prebuilt/abi-dumps/<lib_type>/<platform_sdk_version>/.
Assign the corresponding prevVersion with the current stage and generate
mk commands to diff source and previous dump to
{fileName}.{prevVersion}.abidiff with diff flag --allow-extension and
--advice-only
The test is verified in all stages. lsdumps should be prepared in
advance.
For stage 1: current/ and PLATFORM_SDK_VERSION/
For stage 2: current/ and {PLATFORM_SDK_VERSION-1}/
For stage 3: PLATFORM_SDK_VERSION/ and {PLATFORM_SDK_VERSION-1}/
The definition of stages could be found at
"go/cross-version-abi-check#bookmark=id.vpflkul2z968"

Test: make libbinder_ndk
Bug: 238387082
Change-Id: Ic29456113a541650c75fa38c5c4f2d6d2e76a877