Warn the user if the file cannot be analyzed (because it is missing from the compilation db)

[dkrupp]

Warn the user if a file cannot be analyzed (because it is missing from the compilation db, syntax error) and so "reports in current file" list is invalid.

Today, no error is shown, and the analysis is shown as successful.

This warning should be given in the "Reports in the current file" window to show the user that no report list can be shown because of an error.

[dkrupp]

To proceed with this, CodeChecker parse should give more info about the anlysis state.
Ericsson/codechecker#4100

[dkrupp]

Also give warning if the file had analysis failures.