Allow deleting pre-built or source only for del-download

[crazywhalecc]

What does this PR do?

Allow deleting pre-built or source only for del-download:

• bin/spc del-download --pre-built-only XXX
• bin/spc del-download --source-only XXX

Sometimes we need to test either source or pre-built at the same time. It's just a little function to help us simplify the download procedure. (sometimes download from another side of the earth is quite slow)

Checklist before merging

If your PR involves the changes mentioned below and completed the action, please tick the corresponding option.
If a modification is not involved, please skip it directly.

• If you modified *.php or *.json, run them locally to ensure your changes are valid:
  • PHP_CS_FIXER_IGNORE_ENV=1 composer cs-fix
  • composer analyse
  • composer test
  • bin/spc dev:sort-config
• If it's an extension or dependency update, please ensure the following:
  • Add your test combination to src/globals/test-extensions.php.
  • If adding new or fixing bugs, add commit message containing extension test or test extensions to trigger full test suite.

[henderkes]

I think it's a bit overkill and I probably won't ever use it given that I never use prebuilt sources, but why not.