Investigate binary AST storage

[RedMser]

Games could store the AST in a binary serialization, so that parsing of .ftl files is not required at runtime. This could be done in a conversion step by an editor import plugin (related to #1). Formats like .png get imported and remapped to a .ctex file, this would be a similar approach.

This saves disk space, can combine multiple files into one, and could minify the data by e.g. removing all comment tokens.

See projectfluent/fluent-rs#352 for upstream support, although unlikely to happen.

Since fluent_bundle::FluentResource only takes a String as input, might need to use a compatible trait and/or insert entries by hand.

[RedMser]

Parser already removes comments internally, so they're only really wasting disk space. Likely not worth the additional implementation effort.

Not sure how much of a difference merging files would make, should investigate whether Mozilla do this manually / if the lib does it automatically / if this helps anything at all.