Adding type hints to the code

[XDRAGON2002]

Although static declarations are present in the codebase, it is not uniform throughout.
This issue aims to get the entire project typed, so as to allow mypy enforcement in the future.
I believe working on this issue will help anyone trying to familiarize themselves to the project structure (also helps with easy and friendly PRs)

cve_bin_tool/version_signature.py
cve_bin_tool/version_scanner.py
cve_bin_tool/util.py
cve_bin_tool/cvedb.py
cve_bin_tool/csv2cve.py
cve_bin_tool/file.py
cve_bin_tool/strings.py

These are some of the places which would serve as good starting points.
Also there might be more places where typing needs to be added, that I might have missed here, feel free to open a PR for them as well.

[XDRAGON2002]

Roping in @terriko for verification of issue and adding of "good-first-issue/beginner/easy" issue tag for visibility.

[terriko]

We actually already have a similar open issue that has the flags:

• related Add type hints #761

But in the interest of making this easy for folk to find at the top of the latest issue list, I'm going to leave them both and put the correct tags on this one.

[attreyee-muk]

@terriko can I work on this issue? I am a beginner.

[gaurav879]

I would like to work on this issue.

[terriko]

Anyone interested on working on this: I'm filing some new issues on specific files, feel free to grab one if you want!

[kishan3]

I am interested thank you.

[terriko]

Anyone interested:

I'm still filing new issues for specific files. If there's none available, you can check yourself to see what mypy errors remain by installing mypy using

pip install mypy

Then running

mypy cve_bin_tool/

or

mypy test/

And seeing what files still have errors. You can open your own issue for any file that I don't already have an issue set up for, and open your own PR for any file that still has errors and no open PR fixing them.

[terriko]

Closing all the mypy/type hint issues because I'm not prepared to work on them right now and I don't want new contributors to trip over them first. Some of them have been solved but weren't closed properly, some have open pull requests in progress and will be closed eventually, some could benefit from re-running mypy.