[BUG] IndentChecker for pylint uses reserved message symbol prefixes

[DanielNoord]

Describe the bug
As discussed in:
#481 (comment)

Currently, the IndentChecker for pylint defines two new messages:
https://github.com/PyCQA/prospector/blob/c31bb80d61d49d37a1fe67635aae22f5896111ed/prospector/tools/pylint/indent_checker.py#L15-L24

However, these messages are prefixed with 03. According to the official pylint "documentation" that prefix is actually reserved for pylint's own messages. See:
https://github.com/PyCQA/pylint/blob/0fb6a120c6f0fbc94e305542fe29e790274be096/pylint/checkers/__init__.py#L52

The messages should therefore probably be renamed to use a 51+ prefix.
The old-name system could be used for this, although that might create issues when pylint starts defining W0314. I'll leave the actual resolution of this "bug" up to the maintainers.

[carlio]

Thanks @DanielNoord - I'll look into this. I wonder if this checker is no longer necessary, as I suspect pylint already checks for mixed spacing/tabs now. This checker was written about 8 years ago!

It's odd that I used plugin-specific ranges for pylint-django but forgot that and used the 03 prefix for format messages in prospector 🤷

Either I'll remove this checker or rename the message IDs.

[DanielNoord]

Oh well 😄

If you're going through the effort of checking whether pylint already does this, it might make sense to see if this can be ported? If it has been working without issues for 8 years it might be a good addition to pylint itself? It could be added to the CodeStyleChecker?

[Pierre-Sassoulas]

Mixed indentation is checked by python itself, we removed it from pylint in pylint-dev/pylint#3578

[carlio]

Closing as I have removed this checker from prospector now.