Enable manual run for caching, hackage and build workflows

[jneira]

• Those workflows are not being triggered on pull request and use branch names to trigger them is a little bit clumsy
• This way we could, for example, manually trigger caching on any branch, to control the cache behaviour: this can lead to slow ci builds so you have to know what are you doing (experimenting in your own fork if possible before)
• Here there is docs on how to do the manual trigger: https://docs.github.com/es/actions/managing-workflow-runs/manually-running-a-workflow

[Anton-Latukha]

Great. I didn't know that.

Give people the ability/flexibility to run workflows manually - definitely seems like a good design here.