Fix T97533: Extrapolation of NLA strips outside current view are not rendered

Do a more thorough search for strips that are not visible themselves,
but still influence the viewed time range.

The problem before was that tracks not immediately visible would not be
drawn at all. The strategy for fixing this was to simply include strips
that are visible only because of their extrapolation mode.

To do this, there is now a new function `get_visible_nla_strips` which
gives a first and last `NlaTrack` that needs to  be drawn.

Tagging along with this is the removal of the strip index indicator from
the name on meta tracks. Because of the new structure of the code, it
would incur a performance penalty to restore the previous behavior
(requiring a linear search for the index). Since this number is of
virtually no utility to the user anyways (it has the look & feel of
developer debugging information), this is something I think we can
safely remove without regret.

Reviewed By: sybren

Differential Revision: https://developer.blender.org/D14738

0 files changed, 0 insertions, 0 deletions