Added option to turn off PDB file parsing

[peterbudai]

About

This pull request adds a new setting to the option page dialog. This setting controls whether the PDB files should be parsed at all.
The default setting maintains the original behavior of parsing symbol information.
The effects of disabling PDB parsing are as follows (mentioned in the description of the setting):

• Test discovery becomes significantly (less than 1s instead of more than 10s) faster for large test binaries
• Test execution also becomes significantly faster, due to the faster test discovery phase before each run
• GTA_Traits.h style traits will not be processed
• Regex-based traits discovery will still remain effective
• Test source file location will not be displayed in the Test Explorer window, because it is also obtained from the PDB

Background

Our project outputs some pretty large test binaries. Associated PDB files are tens of megabytes large with hundreds of thousands of symbols. Parsing PDB files this large via MS DIA SDK takes considerable amount of time. Moreover, it seems that DIA SDK sometimes (3 out of 5) simply returns empty list of symbols. In these cases, test traits regexes are not processed, making empty set of traits.

If a project does not make use of the GTA_Traits.h-style traits, only test name regex based, then parsing PDB files are not required, but adds ten seconds delay to every test run for test discovery.
This comes with a compromise that test source file/line information is also lost.

[csoltenborn]

Thanks for your pull request. At first glance, your use case for that option sounds reasonable. Please give us a couple of days to discuss and review your code changes (and the broken build, which - again at first glance - doesn't look like it's caused by you).

[csoltenborn]

Your pull request seems to be just fine - we would just have preferred that you would have added some tests, e.g. to prove that Dia indeed isn't called (we try to take regressions seriously). However, I admit that this currently isn't trivial and requires some refactoring, thus I will take care of that myself.

Thanks for the nice work!