refactor(interface): Update annotation_snippets emitter

[quangloc99]

Resolve #592

I think the linked issue explains the motivation well enough. I'll list the considerations and changes here for clarity:

• I tried to preserve the ported code as much as possible. So code from Rustc
  that are duplicated or not well structured are kept.
• There are some naming differences.
• We do not need to handle translation like in Rustc.
• In Rustc code, the parameter is consumed, while in Solar code, it is passed by reference or Cow.
  There are part that data is cloning to preserve the ported code behavior.
• Some parts like FileName and source code handling are simplified as Solar
  does not need to handle as much cases as Rustc.
• There is a minor change in the behavior of the emitter. Currently, Solar emits
  the diagnostic in 4 parts, while Rustc does not separate into parts at all.
  I made the change to keep the footer part, and the rest are combined into one like in Rustc.
• This change make the old code in diagnostics/emitter/rustc.rs completely obsolete.
  I still kept it though in case that FileWithAnnotatedLines::collect_annotations's behavior is more desired.

Overall, there is only one test output changed, which is due to the mentioned change in emitter behavior.
I'm surprised that the behavior stayed mostly the same.

Please take a look and let me know if there are any issues. I think the code can be refactored further, either in
this PR or in a separate one.