Suport for drop/take messages to map lanes.

[horned-sphere]

Removes unused iterator module from the persistence crate.
Adds support for drop/take messages to map lanes.

[codecov]

Codecov Report

Attention: Patch coverage is 47.91667% with 100 lines in your changes missing coverage. Please review.

Project coverage is 49.34%. Comparing base (b800567) to head (a256426).

Files with missing lines	Patch %	Lines
server/swimos_agent/src/lanes/map/mod.rs	46.48%	99 Missing ⚠️
server/swimos_connector/src/generic/mod.rs	85.71%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #738      +/-   ##
==========================================
- Coverage   49.36%   49.34%   -0.02%     
==========================================
  Files         401      401              
  Lines       34821    34994     +173     
==========================================
+ Hits        17190    17269      +79     
- Misses      17631    17725      +94     

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[SirCipher]

For consistency with the Java implementation, should this not be something like projection: for<'a> fn(&'a C) -> &'a MapLane<K, V, BTreeMap<K, V>> (once your abstraction PR has been merged)?

[horned-sphere]

The next PR adds an optimization that alters how it computes the prefixes/suffixes for the case where the backing map is ordered, so it will be more efficient for BTreeMap (and falls back to this implementation for HashMap).