[V2] Remove support of Mongoose

[LoicPoullain]

Issue

Mongoose brought many problems in the past while maintaining the framework. It takes time to maintain it and it is also not typed and does not seem to be used by FoalTS users: https://www.npmjs.com/package/@foal/mongoose.

FoalTS will no longer provide Mongoose tools starting from v2 (i.e. CLI code generation and the fetchUser function). Users will still be able to use it "by hand" if they wish.

Closes #668.
Closes #559.

Solution and steps

• Remove @foal/mongoose
• Remove all other mentions of mongoose
• Remove the MongoDB tutorial. With the new createapp --mongodb generation, the code is almost the same as in the SQL Simple To-Do List so there is no need anymore to have a separate tutorial for this.

Breaking changes

• @foal/mongoose package is removed. If needed, users can copy past the 10-line code.

Checklist

• Add/update/check docs (code comments and docs/ folder).
• Add/update/check tests.
• Update/check the cli generators.