versionize: rework of the from/into/convert feature to allow conversion with generics

[nsarlin-zama]

closes: https://github.com/zama-ai/tfhe-rs-internal/issues/748

PR content/description

The Versionize proc macro accepts some arguments that will affect the implementation of the traits. From example, the #[versionize(SerializableMyTypeVersions, from = SerializableMyType, into = SerializableMyType)] will apply a conversion method before the versioning, like serde does: https://serde.rs/container-attrs.html#from. However before this PR, this parameter did not work if the conversion type had generics, or if the conversion method needed specific bounds.

On a side note, the syntax was a bit updated. The from/try_from/into keywords were used to mimic serde, for user convenience. However in Versionize we actually don't support having a different value for from and into. This is now checked during the argument parsing. New shortcut arguments have also been added: convert/try_convert. They work the same way except that you only need one argument: #[versionize(SerializableMyTypeVersions, convert = SerializableMyType)].

On the same topic, before this pr the attribute required the to state the name of the dispatch enum in that case: #[versionize(SerializableMyTypeVersions, from = SerializableMyType, into = SerializableMyType)]. This is now automatically detected when we use a conversion, which means that the attribute can be simplified as #[versionize(convert = SerializableMyType)]

Check-list:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)
• Relevant issues are marked as resolved/closed, related issues are linked in the description
• Check for breaking changes (including serialization changes) and add them to commit message following the conventional commit specification