CodeChecker incremental analysis leaves outdated analysis results in the report directory

[dkrupp]

If the compilation action changes for a file in the compile commands.json (for example the cmake is reexecuted), new plist files will be generated for the same file. then the old plist files will never be updated and remain in the report directory.

This is so, because name of the generated plist files contain the hash of the compilation action.

In incremental mode, when a source file is reanalzyed, CodeChecker should clean up all earlier outdated analysis results for that source file.