[tech] [doc] Centralize fmt, clippy & test in makefile

[pbougue]

Centralize in makefile and expose in doc and CI

Also:

• rm system package for install_proj (+ comments and cosmetic refactor)
• minor doc update after update on TT (https://github.com/CanalTP/tartare-tools/pull/103#discussion_r451521210)

TODO:

• bump version > No need, "major" bump in another PR

Ref. ND-947

[woshilapin]

Just, we used makefile instead of Makefile in other repositories so far. Maybe let's try to keep it consistent. Let's keep it as a Makefile, my sample was small and actually, Makefile is far more frequent.

[woshilapin]

Suggested change

	cargo test --workspace --all-features
	cargo test --workspace
	cargo test --workspace --all-features --all-targets
	cargo test --workspace --all-targets

[pbougue]

As discussed, this removes doctests.
See rust-lang/cargo#6669 and https://doc.rust-lang.org/cargo/commands/cargo-test.html

So adding this and the corresponding lines to just trigger doctests.