Ensure --overwrite flag is only passed once

[henrymercer]

This fixes a bug where if CODEQL_ACTION_EXTRA_OPTIONS specified that --overwrite should be passed to database init, the --overwrite argument would be passed twice, leading to an error.

To accomplish this, I introduce an ignoringOptions argument to specify options in CODEQL_ACTION_EXTRA_OPTIONS that should be ignored. It would be nice to have a general solution that didn't require specifying which options should be ignored, but the problem with that is that it does make sense to pass some flags more than once.

Merge / deployment checklist

• Confirm this change is backwards compatible with existing workflows.
• Confirm the readme has been updated if necessary.
• Confirm the changelog has been updated if necessary.

[angelapwen]

Makes sense — did you include --expect-discarded-cache because that's another obvious one that should only be passed once? I wonder if that one should also be part of the changenote (though I guess then the note would need to be more generalized so we don't have to write a note each time we pass ignoringOptions).

[henrymercer]

Makes sense — did you include --expect-discarded-cache because that's another obvious one that should only be passed once? I wonder if that one should also be part of the changenote (though I guess then the note would need to be more generalized so we don't have to write a note each time we pass ignoringOptions).

I had a quick scan through and that was the most obvious other one to add. I'll just include --overwrite in the changelog note though as I don't think we've advised customers to specify --expect-discarded-cache manually.