Optimize Subarray::compute_relevant_fragments

[joe-maley]

This patch refactors Subarray::compute_relevant_fragments to reduce the time
complexity at the expense of false-positive relevant fragments. The correctness
of the tile overlap computation is unaffected because it will not find overlap
within falsely relevant fragments.

Currently, this routine has a time complexity of:
<# dimensions>[product]<# dimension ranges> * <# fragments>

This patch modifies the routine to have a time complexity of:
<# dimensions>[summation]<# dimension ranges> * <# fragments>

Currently, a single relevant-fragment-bytemap is computed by checking overlap
on each fragment's ND-range against the ND-range for each flattened range
ids.

This patch maintains an individual relevant-fragment-bytemap for each
dimension, where the bytemap is computed by checking overlap on each fragment's
ND-range against each ND-range in subarray. The final relevant-fragment-bytemap
is computed by performing a logical AND among each dimension's individual
fragment bytemap.

The important consideration is that the input to this routine is a start/end
index on the flattened range ids. To reduce risk, this change does not modify
the interface to Subarray::compute_relevant_fragments. To compute in ND-space
instead of flattened-space, we must convert the input start/end indexes to
ND-coordinates. The ND space between the start/end coordinates is not guaranteed
to encapsulate all ranges in between the flattened ("total order") start/end
indexes. To handle this, we must expand the coordinates to sufficiently capture
all input ranges. This may add additional ranges, which may result in false
positive relevant fragments.

---

TYPE: IMPROVEMENT
DESC: Optimize Subarray::compute_relevant_fragments

[github-actions]

The backport to release-2.2 failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-release-2.2 release-2.2
# Navigate to the new working tree
cd .worktrees/backport-release-2.2
# Create a new branch
git switch --create backport-2216-to-release-2.2
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick --mainline 1 0b8d52fe6f5e2492cc6daa0472cc9720664d57d9
# Push it to GitHub
git push --set-upstream origin backport-2216-to-release-2.2
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-release-2.2

Then, create a pull request where the base branch is release-2.2 and the compare/head branch is backport-2216-to-release-2.2.