Update deployment pipeline for supporting release packages using env vars.

[Pasarus]

• Ensure that it is uploaded to the main channel on Mantid, instead of the nightly labelled channel.
• Ensure the versioning changes in conda-recipe are release aware perhaps adding a permanent tag?
• Windows signing needs to be handled i.e. not deployed automatically.
• Adapt the current deployment strategy for release to include either 1. Release candidates or 2. A new job that deploys manually like the previous system (Use option 2 unless decided otherwise)
• How do we handle documentation?

[martyngigg]

We're going to have to do some of this manually again this time.

[thomashampson]

I think this is already implemented, but will have to check.

[thomashampson]

This has been implemented