fix: grid labels hidden on false overlap at rotation=90

[guillermodotn]

Rationale

Gridline labels hidden at rotation=90° due to intersects_path() false positives on collinear edges.

Fixes #2394.

Implications

Adds a bbox pre-check before intersects_path(); if bboxes don't overlap, skip the path check. Tilted geo labels unaffected.

[rcomer]

Thanks for this @guillermodotn. My only worry is that calling get_extents here will slow down what is already a pretty slow draw. Since we call check_overlapping on every pair of visible labels, the time increases with order N**2. Could we instead call get_extents once for each label and attach the extents to the label alongside the path here? I tried locally by timing this particularly slow test and it does seem to make a difference (unless I made a mistake...)

[rcomer]

Also you have a typo in your commit/title: 9 -> 90

[guillermodotn]

Thanks for pointing to where to cache it and the benchmark test.

Fixed both.