Summary:
For a long array with removals proportional to that length,
lodash/pullAt becomes slow due to doing one splice per removal.
This diff swaps in an alternate implementation that doesn't become
quadratic. On a 250k-row doc with a row-level access rule, this improves
initial page load for a viewer with access to half the rows from minutes
to seconds.
Test Plan: added test; did manual benchmarking
Reviewers: dsagal
Reviewed By: dsagal
Differential Revision: https://phab.getgrist.com/D2777