Add Inject instances for Eons. Deprecate old eons conversion functions.

[carbolymer]

Changelog

- description: |
    Deprecate eons conversion functions like `conwayEraOnwardsToBabbageEraOnwards`. Add [`Inject`](https://cardano-ledger.cardano.intersectmbo.org/cardano-ledger-core/Cardano-Ledger-BaseTypes.html#t:Inject) instances for eon conversions. See the PR description for migration aid.
# uncomment types applicable to the change:
  type:
  # - feature        # introduces a new feature
  # - breaking       # the API has changed in a breaking way
   - compatible     # the API has changed but is non-breaking
  # - optimisation   # measurable performance improvements
   - refactoring    # QoL changes
  # - bugfix         # fixes a defect
  # - test           # fixes/modifies tests
  # - maintenance    # not directly related to the code
  # - release        # related to a new release preparation
  # - documentation  # change in code docs, haddocks...

Context

Use Inject for eons conversion instead of specialised and hard to remember functions.

You can migrate your codebase using this snippet:

find . -type f -name "*.hs" -exec sed -i \
  -e 's/allegraEraOnwardsToShelleyBasedEra/inject/g' \
  -e 's/alonzoEraOnwardsToShelleyBasedEra/inject/g' \
  -e 's/babbageEraOnwardsToShelleyBasedEra/inject/g' \
  -e 's/conwayEraOnwardsToShelleyBasedEra/inject/g' \
  -e 's/conwayEraOnwardsToBabbageEraOnwards/inject/g' \
  -e 's/maryEraOnwardsToShelleyBasedEra/inject/g' \
  -e 's/shelleyEraOnlyToShelleyBasedEra/inject/g' \
  -e 's/shelleyToAllegraEraToShelleyBasedEra/inject/g' \
  -e 's/shelleyToBabbageEraToShelleyBasedEra/inject/g' \
  -e 's/shelleyToMaryEraToShelleyBasedEra/inject/g' \
  -e 's/babbageEraOnwardsToEra/inject/g' \
  -e 's/eraToBabbageEraOnwards/inject/g' {} +

Corresponding CLI PR: IntersectMBO/cardano-cli#969

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated. See Running tests for more details
• Self-reviewed the diff

[smelc]

Nice QoL change 👍

[Jimbo4350]

We are adding an additional step to the deprecation of these era conversion functions where what we should be doing is figuring out how to change the interface then deprecating and eventually remove the functions. Creating Inject instances for them seems to be an additional unnecessary step.

[carbolymer]

@Jimbo4350 the goal of this PR is to make the codebase more pleasant to work with until we get rid of Eons. There's still significant amount of work left to do, before we arrive there.

I disagree that it adds an additional step in deprecation, I see Inject as a general purpose tool for total conversions from one to the another type. Those Inject instances would be gone together with Eons as well.

If you think this PR is changing too much, what do you think of just using inject in the glue code for experimental API. I mean the changes in cardano-api/internal/Cardano/Api/Experimental/Eras.hs ?