Refactor bundle and manifest validation logic

[ritave]

This is a prerequisite for #2565.

The snap bundle validation logic is old and should be refactored. Validation is split into multiple locations, sometimes only the first error is shown instead of all errors, fixing logic is not scalable since it's a big switch case and not abstracted nicely.

The goal is to refactor validation into rules based abstraction similar to eslint and SIP validator tool, where each rule is a separate file and each rule manages it's own list of errors and fixes.