Alexandria API improvement

The alexandria API is causing some boilerplate in the irdest-core storage code. Some things are missing to improve the situation.

• Rename .batch(...) to .batch_insert(...)
• Add .batch_update(...) next to .update(...)
• Add .upsert(...) and .batch_upsert(...) as combinations of the above functions
• Provide a derive macro for ToDiff
  • Create alexandria-derive (or alexandria-macros?) crate to let ircore-types depend on it, without having to depend on the whole database.