MCAP importer preserves ROS `/tf_static` message timing

MCAP importer preserves ROS /tf_static message timing

The MCAP importer no longer maps the ROS /tf_static topic to Rerun static data. It now preserves the original MCAP message timestamps.

This does not impact schema stability for registration on an existing catalog dataset. However, if you used queries that previously used the static-only index, you may need to adapt them to use an index:

# Before
df = dataset.reader(index=None)

# After
df = dataset.reader(index="message_log_time")

Rationale for this change:

• ROS' TF buffer requires the static-transform semantic because it otherwise works on a rolling time window. In contrast, Rerun doesn't require this concept because it doesn't use a time window and can retrieve transforms through a latest-at query from the first time they appear onward.
• message_log_time and message_publish_time can show when a transform appeared and help diagnose an incomplete transform tree.
• Foxglove frame transforms on /tf_static already behave this way.