Add `--include-git` to `mix igniter.upgrade --all`

**Is your feature request related to a problem? Please describe.**
A client was surprised by the behaviour of `igniter.upgrade` not matching that of `deps.update` for git-based dependencies.

**Describe the solution you'd like**
Either `--all` should include git dependencies by default or it should have an additional flag to enable them.

**Describe alternatives you've considered**

```
mix igniter.upgrade --all && mix deps.update --all
```

**Additional context**
Request via an APS client.

Start by locating the option parsing and upgrade handling for `mix igniter.upgrade --all`, then compare how git-based dependencies are handled by `mix deps.update --all`. The issue is done when `--include-git` enables git dependencies during an `--all` upgrade, with the intended behavior covered by the relevant tests if they exist.

Written by the indexing model from the issue text.