Allow UnrealObjectPtrTool to perform reverse upgrades when the "-r" commandline argument is used. Also added functionality to allow UnrealHeaderTool to dump out necessary log messages specifying TObjectPtr member declrations for UnrealObjectPtrTool to consume.
Tested by:
1) Performing a new forward pointer upgrade (from a new UHT log) and confirming the resulting files had zero diffs when compared to a shelf of upgraded files from previous version of UnrealObjectPtrTool.
2) Performed a forward pointer upgrade, then a reverse pointer upgrade then reverted all unchanged files. The remaining files (13 of them see shelved CL15213431) only had trailing whitespace corrections due to the deliberate choices for trailing whitespace manipulation when doing forward upgrades.
#rb devin.doucette
[CL 15219628 by Zousar Shaker in ue5-main branch]
