feat: Upload of multiple files

[mauroerta]

🤔 Problem

If you're working in a mono repo or simply you'll like to know the projects that are searching for funding in multiple of your repositories, it could be a good option to upload multiple package.json all in once and obtain the information of all of them.

🚑 Solution

Allow multiple file uploads and merge the dependencies of all the package.json, then the process of fetching the data from npm / GitHub would remain the same.

💡 Alternatives I've considered

Another Idea could be to automatically obtain all the package.json of all the repositories of a GitHub/Gitlab/Bitbucket user, so instead of uploading the files, the user can just log in and then Sponsorhello can ask for the necessary permissions and do the dirty job. In the case of GitHub tho, there is no need to implement this feature since is already available here