Resolves https://github.com/tuist/tuist/issues/452
### Short description
To support workflows where only the local project needs to be re-generated without re-generating all its dependencies a new generation option is needed (see https://github.com/tuist/tuist/issues/452 for full rationale)
### Solution
Add a new option to generate the local project only.
usage:
```bash
tuist generate --project-only
```
### Implementation
- [x] Expose new generator method that generates a single project
- [x] Expose new option via command line argument `--project-only`
- [x] Update documentation
- [x] Update changelog
### Test Plan
- Run `tuist generate` within `fixtures/ios_app_with_custom_workspace`
- Verify the workspace is still generated with all the dependencies as before
- Run `tuist generate` within `fixtures/ios_app_with_custom_workspace/App`
- Verify the project workspace is still generated with all the dependencies as before
- Run `tuist generate --project-only` within `fixtures/ios_app_with_custom_workspace/App`
- Verify only the `App`'s project re-generated (this can be done by either doing a git clean before running the command and then verifying that the only Xcode project is for `App` or by manually modifying any of the projects and verifying they don't update)
* Dete the documentation that was generated by jazzy
We don't see value in generating documentation for internal interfaces so we decided to remove the Jazzy auto-generated documentation and bring the documentation from the tuist/documentation repository into this one.
* Delete references to Open Collective and include a documentation section that lets user know about the documentation folder.
* Remove the step to generate the documentation from the release steps
* Merge documentation from the documentation repository
* Update CHANGELOG
* Address comments
* Adding integration tests for up
- Introduced new up cucumber test
- Fixed an issue with `System.run` where valid commands that returned non-zero exit codes were not throwing (e.g. `ls some_file_that_does_not_exist`)
- Updated README with additional instructions on how to run unit and acceptance tests
Test Plan
Verify unit tests pass
- `swift test`
Verify acceptance tests pass
- `rake features`
* Extract Up command from the project graph
* Update CHANELOG.md
* Update documentation
* Lint all up actions before running isMet and meet
* Fix up.rb formatting
* empty commit to trigger CI
Kas