Consider a different issue tracker solution for GrimoireLab

**Proposal:** Adopt a single issue tracker for GrimoireLab and use "labels" or something similar to indicate which component an issue is for. This can be a GitHub native issue tracker or a third-party solution.

**Rationale:** GrimoireLab is using GitHub native issue tracker. However, the issues are spread across different repositories for the different modules. This makes it difficult to search and find issues, producing duplicates and frustration on both user and maintainer side.

/cc @sduenas @valeriocos @jsmanrique