Add dependency as possible scope filter variable

[JustinGOSSES]

Make code dependencies a possible scope variable.

Users might want to search for code that uses a particular dependency or combination of dependencies and mentions a specific string.

For example, they might want to work with pytorch and a specific API and are looking for examples.

Alternatively, the owner of the API might want to gain a better understanding of how different types of developers are using their service. Do users of a certain dependency use that dependency to process the data from the API in a different way than other users resulting in a common problem?

This type of filtering capability would be advantageous for situations where the users doesn't know if code already exists but has an idea what dependencies they are interested in having been used. Filtering by dependency also allows for more generic strings to be searched for as the filtering by dependency improves signal to noise in results.

It would also be useful when the name of the dependency is not mentioned in the same file as the other string being searched as can sometimes happen. For example, in the "pytorch and API URL" scenario above, the string "pytorch" and the API URL could easily be in different files, so search for "pytorch" as a string would miss many valuable results that would be caught if filtering was done by dependency metadata.