Add `.upload()` to `SourceMaps` class

[s1gr1d]

Description

Uploading source maps is possible with Releases.uploadSourceMaps(). However, releases and source maps can be handled individually and for separation of concerns, this functionality can be added to SourceMaps.upload().

We can keep both functions for backwards compatibility.

See comment: #3088 (comment)

[linear]

CLI-277