Add support for non MCF validation

This topic was raised during the code sprint:

When we are transforming from a more relaxed schema to another more restrictive, it is possible that the result will not be compliant with the output schema, as we are not validating the output.

I took a look on how this could be implemented, and here are my thoughts about it:

- The current `validate` command is a proxy to `validate_mcf`
- I understand that we want to keep `validate_mcf`, as it is used in the `pygeoapi_plugin`
- Validation can be useful on its own, not only when transforming
- The commands that accept an MCF as an input are different from the commands that accept metadata in other schemas

The path I am following is:

- Add a `validate` method to `BaseOutputSchema`
- Add `can_validate` to the `schema_matrix` elements in `get_supported_schemas`
- Add `validate` to the `schemas` click command from `get_supported_schemas`
- Modify the `get_supported_schemas` to filter by schemas that can validate?
- Add a `validate` option to the `transform` click command using the previous filter when calling to `get_supported_schemas` to build the list of choices
- If the option `validate` is present, call to `schema_object_output.validate(content)` in `transform_metadata`

The questions I have are:

- What to do with `can_validate` in `get_supported_schemas` for `include_autodetect`
- Should we add the filter by validate in `get_supported_schemas`?
- How to generalize the `validate` click command? It seems like a design decision to have differentiated the commands that accept MFC from the ones that accept metadata in other schemas, so a unification might break that principle

I will reference a branch in my fork to show all the details mentioned in this issue.