Make recipes translatable

At least YAML 1.2 allows for tags that allow us to define custom data types https://yaml.org/spec/1.2.2/#tags, then we would need to respond to the !translate type with wrapping it in translation at runtime and extracting it statically. Not sure how wide support for this is in tools.

key: 12
another: !translate This text will be translated

The default (failsafe) schema of YAML does not include !translate, however

All nodes with the “!” non-specific tag are resolved, by the standard convention, to “tag:yaml.org,2002:seq”, “tag:yaml.org,2002:map” or “tag:yaml.org,2002:str”, according to their kind.

per https://yaml.org/spec/1.2.2/#failsafe-schema -- which I understand that tools are expected to resolve custom tags as sequence, map or string based on which syntax was used above them. So !translate followed by a string would/should be understood as string when applied to a string by a YAML tool following the failsafe schema.

Adding related issues.

We'll need to figure out too:

* Potx support
* l.d.org support: we need to run potx on general projects that include a recipe.yml.

Any news here?

Looks like the Symfony YAML parser supports custom tags: https://symfony.com/doc/current/components/yaml.html#parsing-and-dumping...

Maybe something we could take advantage of here?