ci: add build workflow for release candidate builds

[CharlieMc0]

Description

Adds a new workflow for release candidates that includes a set of binaries under a "prerelease" GitHub release.

This is one step towards the new CI workflow

Will not work until #1144 is merged in.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Limited testing - we can't really test this until after it has been merged in and the workflow is active.

Checklist:

• I have added unit tests that prove my fix feature works

[lumtis]

LGTM

These are changes where it might make more sense to require reviews from the infra team for merging.

Maybe we could set a CODEOWNER set for CI related PR?

# Primary repo maintainers
*             @protocol-team

# CI maintainers
.github/      @infra-team

[CharlieMc0]

Replace by #1218