Request for merging HLKX during HLKX Generation

[kostyanf14]

Based on #641 (comment) and #641 (comment)

Need to implement 3 independent modes:

1. Merge during testing. AutoHCK merges provided HLKX packages during the final creation of the HLKX package
2. Merge during testing if present. Add the ability to provide a CLI for another AutoHCK workspace. If it contains an HLKX package when the current run goes to the package creation stage, then perform the merge; if not, just log.
3. Merge only run. AutoHCK merges provided HLKX packages into one package without starting HLK clients and running any testing. Check if HLK allows this.