refactor!: replace Snapshot::try_new_from with SnapshotBuilder::from_snapshot

[zachschuermann]

Note

I'll split up this PR into more reviewable commits if we have alignment on this direction! also note the vast majority of this PR is either code movement or callsite updates.

What changes are proposed in this pull request?

Seeking some early feedback on integrating Snapshot::try_new_from into SnapshotBuilder. This PR has two major changes:

1. Moves Snapshot::try_new_from into SnapshotBuilder with two pieces:
   a. SnapshotBuilder::from_snapshot to specify an existing snapshot for the builder
   b. Migrates all of the try_new_from implementation into SnapshotBuilder::build
2. Modifies SnapshotBuilder:
   a. to now optionally take a table_root - since the snapshot hint passed to the builder includes its own table_root
   b. since Snapshot::try_new_from relies on Arcs to easily return snapshots that are unchanged from the existing snapshot, SnapshotBuilder::build() now returns an Arc<Snapshot> instead of a Snapshot

This PR affects the following public APIs

1. Replaces Snapshot::try_new_from(existing) with SnapshotBuilder::new().from_snapshot(existing)
2. SnapshotBuilder::build() now returns an Arc<Snapshot> instead of a Snapshot
3. Snapshot::builder() signature changed: now it accepts no parameters, and instead has a .with_table_root() method

How was this change tested?

existing

[codecov]

Codecov Report

❌ Patch coverage is 82.63889% with 50 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.63%. Comparing base (5552d21) to head (018e45e).

Files with missing lines	Patch %	Lines
kernel/src/snapshot/builder.rs	84.32%	12 Missing and 9 partials ⚠️
kernel/src/checkpoint/tests.rs	54.54%	0 Missing and 10 partials ⚠️
kernel/src/snapshot.rs	88.31%	0 Missing and 9 partials ⚠️
acceptance/src/meta.rs	40.00%	0 Missing and 3 partials ⚠️
ffi/src/transaction/mod.rs	33.33%	0 Missing and 2 partials ⚠️
kernel/src/table_changes/mod.rs	81.81%	0 Missing and 2 partials ⚠️
acceptance/src/data.rs	66.66%	0 Missing and 1 partial ⚠️
ffi/src/lib.rs	50.00%	0 Missing and 1 partial ⚠️
test-utils/src/lib.rs	66.66%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1277      +/-   ##
==========================================
+ Coverage   83.60%   83.63%   +0.02%     
==========================================
  Files         107      107              
  Lines       25651    25773     +122     
  Branches    25651    25773     +122     
==========================================
+ Hits        21446    21554     +108     
- Misses       3135     3142       +7     
- Partials     1070     1077       +7     

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[zachschuermann]

closing in favor of #1289