Classify invalid paths as unknown paths

[fraviktor]

Summary

• Add XMO_INVALID_PATH_ERR as a recognized API error.
• Map both XMO_INVALID_PATH_ERR and XMO_UNKNOWN_PATH_ERR to UnknownPathException.
• Preserve the router-provided numeric error code and description in the exception arguments.
• Add a sanitized request/action error fixture and test the mapping through the mocked HTTP response path.

Background

Some Sagemcom firmware returns XMO_INVALID_PATH_ERR instead of
XMO_UNKNOWN_PATH_ERR when an XPath is unsupported.

For example, this was observed on a FAST3896 Magyar gateway running
FAST3896_MAGYAR_sw23.83.19.23e:

code: 16777242
description: XMO_INVALID_PATH_ERR

[fraviktor]

Hi @iMicknl !
Unfortunately the pr-labeler can't work with a PR came from a fork, so you can either do the labeler manually and ignore this error or we could figure out how to update it using the TimonVS's gh action.
Maybe if you could push this fix to the "main", changing the
on: pull_request: types: [opened]
to
on: pull_request_target: types: [opened, reopened, synchronize]
then it would solve this. Sadly it won't solve the warnings about Node 20 deprecation, but I don't mind if you can live with it.

[iMicknl]

Thanks!