VS: Add v143 flag tables for VS 17.0 Preview 2
Run the commands
python3 Source/cmConvertMSBuildXMLToJSON.py -t v143 \
'c:/.../2022/Preview/MSBuild/Microsoft/VC/v170/1033/cl.xml'
python3 Source/cmConvertMSBuildXMLToJSON.py -t v143 \
'c:/.../2022/Preview/MSBuild/Microsoft/VC/v170/1033/link.xml'
To generate `Templates/MSBuild/FlagTables/v143_{CL,Link}.json`.
We can re-use `Templates/MSBuild/FlagTables/v14_LIB.json`.