'Rolling Tag' logic for pre/release builds

[CodeGat]

In this PR:

 * cd.yml: Moved tagging logic to before deployment

• ci.yml: Added tagging logic to before prerelease deployment

This fixes up the issue of the spack.yaml file (specifically, the spack.specs access-om2@git.tag) looking to clone the tag that doesn't exist (yet). We add a rolling tag for the prerelease branch so the build can progress, and then when it is merged, place the tag in it's rightful position on the main branch.

This 'rolling tag' logic is noted here:

gitGraph
  commit tag: "2024.01.1"
  branch pre-2024.02.1
  commit tag: "2024.02.1"

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And then when the next commit comes along:

gitGraph
  commit tag: "2024.01.1"
  branch pre-2024.02.1
  commit
  commit tag: "2024.02.1"

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and then when merged:

gitGraph
  commit tag: "2024.01.1"
  branch pre-2024.02.1
  commit
  commit
  checkout main
  merge pre-2024.02.1 tag: "2024.02.1"

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[CodeGat]

Prerelease looks like this:

gitGraph
  commit id: "2024.01.1" type: HIGHLIGHT tag: "2024.01.01"
  branch pre-2024.01.2
  checkout pre-2024.01.2
  commit id: "access-om2_2024.01.2-1"
  commit id: "access-om2_2024.01.2-2"
  commit id: "access-om2_2024.01.2-3"
  checkout main
  merge pre-2024.01.2 id: "2024.01.2" type: HIGHLIGHT tag: "2024.01.2"

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[aidanheerdegen]

Looks good to merge and test.