Remove branch coverage and refactor coverage.py methods for accessing

[eleanorjboyd]

Removing branch coverage from the payload as the initial way it was being discovered / added was not documented / in the coverage.py API and therefore is not guaranteed to be stable. Removing for now with plans to add upstream and re-include in the extension here

coverage PR: #24118

[eleanorjboyd]

this PR also includes a fix where the detail coverage map uses uri.fspath as the key in the resultResolver for consistency:
this.detailedCoverageMap.set(uri.fsPath, detailedCoverageArray);

and added logging