--keep-going in manifest mode should display which packages failed

[ras0219-msft]

After running vcpkg install --keep-going, if packages failed, vcpkg should display specifically which ones. We don't want to print a summary in the no-op case since it's called often as part of user's configure steps.

Classic mode, today

$ .\vcpkg install zlib rapidjson
/* package builds */
Total elapsed time: 16.94 s

RESULTS
    rapidjson:x86-windows: SUCCEEDED: 7.778 s
    zlib:x86-windows: BUILD_FAILED: 196.3 ms

SUMMARY FOR x86-windows
    SUCCEEDED: 1
    BUILD_FAILED: 1

/* usage information */

Manifest mode, today

$ .\vcpkg install zlib rapidjson
/* package builds */
Total elapsed time: 15.79 s
/* usage information */

Suggested manifest mode

$ .\vcpkg install zlib rapidjson
/* package builds */
Total elapsed time: 15.79 s

RESULTS
    zlib:x86-windows: BUILD_FAILED: 196.3 ms

/* usage information */

[Osyotr]

It should also exit with error if some packages failed. Right now cmake will continue configuration even when some packages were not installed.