Closes T2723.

Rework existing mock archive to account for a new graph backend.

Closes T2659.

Rationale: ease batch commit workloads.

Closes T2725.

rationale:
- it is consistent with SwhFS which we are now using in doc
- FUSE is an implementation detail, which has no place in user-facing names
- it is consistent with other FUSE-based FS (sshfs, RepoFS, etc.)

Closes T2708.

Closes T2716.

Closes T2711.

Closes T2709.

Closes T2702

without this click includes the full (long) docstring in the main --help

Closes T2669

Closes T2699.

h/t @haltode

also apply various other minor improvements to the configuration documentation:

- mention and show in the example the outer "swh > fuse" stanza
- fix sphinx markup for verbatim text (it's "``", not "`")
- add configuration file doc to the doc index

- Closes T2705: move --config-file to "swh fuse".
- Closes T2678: add default configuration location.

Closes T2665.

in particular:
- drop the TODO about separate cache DBs (now done)
- drop the examples part (we will have a tutorial/walkthrough)
- add reference to task dedicated to sharding

Do not unnecessarily prefetch information before accessing it directly.

as the alternative switch to --foreground

Fixes T2698.

Closes T2664.

- API data generation script can now easily prefetch content raw data,
  revision parents, etc.
- Use the Rust compiler as testing repository (contains more corner
  case, such as submodules)
- Mount test artifacts on the fly

Move the lookup() code logic into FuseEntry class.

Closes T2663.

- Add a `SymlinkEntry` class (+ rework fs/ class init using dataclasses)
- Support symlinks, submodules, and mounting revisions
- Basic unit tests for revision artifacts

Closes T2673.