feat: add recursive dependency search for imported contracts

[rkolpakov]

Added possibility to verify contracts if they have dependencies. Used a recursive search over the repo on github to cover complex contracts e.g. EasyTrack.

[TheDZhon]

Thank you for proposing this change 🙏

Let me shed a bit of light here 🤔
So the issue arose with the brownie verification tooling (i.e., they rewrite the imports on the sources submission)

See the attached pics:

I suggest NOT enabling recursive ('fuzzy') search by default but instead utilizing it only if the enforcement flag is provided within the config. Also, the flag might be omitted to preserve backward compatibility, falling back to the previous (strict search) behavior.

wdyt, @rkolpakov and @mymphe?

[arwer13]

I'd prefer it enabled by flag (NOT default) as well. Although I cannot come up with an example when enabling this by default would lead to a bad outcome, I'd like to see more strictness in such a bedrock tool.

[mymphe]

Agree with @arwer13. I think this feature is only useful for certain scenarios and should be explicitly enabled. Overall, a tool such as Diffyscan should be as dumb as possible, imo. Making it too smart might lead to critical false positives.

[arwer13]

Thanks for the code and fixes! Almost there from my point of view, left just a pair of minor doc-related comments.