rose suite-run: export Rose and suite engine versions

`rose suite-run` will now export Rose and suite engine versions in the environment and as Jinja2 variables. There is no direct support for the usage of these variables. It is up to the local installation to provide wrappers to ensure that the correct versions of Rose and the suite engine are used.

Using Cylc's `suite.rc` as an example, users of long running suites are expected to add the following lines:
```
[runtime]
[[root]]
initial scripting = """
export CYLC_VERSION='{{CYLC_VERSION}}'
export ROSE_VERSION='{{ROSE_VERSION}}'
```

The would allow the site wrapper to pick up the correct versions of Cylc and Rose in tasks.

`rose suite-gcontrol` and `rose suite-shutdown` should do this automatically.

`rose suite-run --reload` will re-export the original version of Cylc, but it will export the current version of Rose.