Re-evaluate license_finder as the tool to collect dependency licenses

We decided to use license_finder because at that time it supported most of the categories of softwares we use, while omnibus's built-in tool license_scout didn't. However, over the course of time we are seeing license_finder failing to detect dependencies of many Go projects, which resulted in an ever-growing rules file which needs to be populated manually.

Also, we had to do a quick fix MR to ensure dependencies from our Rails component is accurate - at !3700 (merged)

We should re-evaluate our decision to use license_finder and do a bit more research on what is the best tool for this.