Binja database support

[xusheng6]

This PR adds support for loading and analyzing a binja database: #2496

There are two things I wish to mention:

1. This PR is rebased on Various binja backend fixes #2500, rather then the latest master. I now realize this is not the best thing to do, but I cannot simply drop the commits from Various binja backend fixes #2500 because there are conflicts. So maybe first have a look at that PR, and if it gets approved, I can rebase this again (if needed)
2. I did not add a unit test for this. I know I can save one of the file we use for unit tests to a binja database and then load it. Do you have a representative binary to use for it among those files? Also, should I add a new test or should I just add it to test_binja_features.py?

Checklist

• No CHANGELOG update needed

• No new tests needed

• No documentation update needed

[williballenthin]

Do you have a representative binary to use for it among those files? Also, should I add a new test or should I just add it to test_binja_features.py?

I think you should take a trivial file, like PMA 01-01.dll, and use that. The test only needs to show that the db file can be analyzed, not that all the features are extracted consistently (which we can assume will be the case, I think).

[williballenthin]

good catch