Create a documentation of compiler error codes

[WojciechMazur]

Based on https://github.com/scala/scala3/blob/577721f395350461499c3a71a7a0c934aa09109c/compiler/src/dotty/tools/dotc/reporting/ErrorMessageID.scala we should create a documented an searchable list of compiler error codes that can be easily googled by the users. Each entry should contain an explanation of the error, and code snippet triggering the error.

Rusts error codes book can be a good example of such documentation https://doc.rust-lang.org/error_codes/error-index.html

After establishment of original documentation, each new error code introduced to the compiler should be checked in the CI to contain a valid documentation.