Adding render option to the actions "render" and "publish" and cleaning code

[m-fehr]

This pull request addresses the feature in #102

What I did:

• Introduced an optional profile input argument for specifying the profile to give to the render command.

• To simplify the conditional logic the command strings are now dynamically build.

• Moved the Git configuration to a separate step for clarity.

[cderv]

Thanks.

Do you find an explicit profile option to the action easier than using QUARTO_PROFILE env var ?

      - name: Deploy gh-pages Preview
        uses: quarto-dev/quarto-actions/publish@v2
        with:
          target: gh-pages
        env:
          QUARTO_PROFILE: preview

Asking because adding --profile support is adding more cased to handle in the action yaml while it works already using env var.
So I am wondering if as user it seemed easier to have the profile configuration instead of env var.

[m-fehr]

I believe it is more intuitive considering that "--to" is also an explicit profile option.

When I reviewed the README for the render action, I naturally assumed there would be a corresponding render option. However, you could leave it as it is now, but it should be added to the README file.

[cderv]

I have added mention of QUARTO_PROFILE to READMEs

@cscheid are you in favor of adding a new

with:
  profile: preview

option in the action instead of just setting

env:
  QUARTO_PROFILE: preview

Just to get another view on this. Thanks !

[cscheid]

I don't have a strong opinion either way.