Revert fspath deprecation

[nicoddemus]

It is not clear yet how we should proceed with this deprecation
because pytest.Item.reportinfo is public API and returns a py.path object,
and also how plugins and our examples should handle that.

Reverting just the deprecation aspect of #8251 so we can get a 7.0.0 release out.

We will reintroduce the deprecation later once we have a clear path moving forward with replacing reportinfo.

Closes #8445
Closes #8821

[nicoddemus]

As per #8821 (comment), decided to go ahead with a PR, we can accept or decline it here.

If accepted, I will create a follow up issue to reintroduce the deprecation at a later date.

[The-Compiler]

Thanks for picking this up! Seems reasonable, for context, the original deprecation was in #8251.

I agree with what @bluetech has said in #8251 (comment) - let's release 7.0 without this deprecation, and then try to do a proper cut, probably for 8.0.

[The-Compiler]

Oh, I see you're also closing #8445 from this. However, what about HOOK_LEGACY_PATH_ARG introduced in #8463 (as follow-up to #8144)? Do we want to keep that deprecation or should it be reverted as well? If we keep it, do we have enough docs for it (I think we do)?

[nicoddemus]

If we keep it, do we have enough docs for it (I think we do)?

I think the docs are good as they are, because the upgrade path is clear.

Node.fspath is different because one can't reasonably implement the public reportinfo API without hacks, so better do postpone it.

[nicoddemus]

Created follow up issue: #8908