Simplify implementation for KVStore trait objects

[wvanlint]

The implementation of the Persist and Persister trait for KVStore types can also be used for trait objects if there is no implicit bound of Sized.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.49%. Comparing base (beef584) to head (a65748f).

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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2976      +/-   ##
==========================================
+ Coverage   89.46%   89.49%   +0.02%     
==========================================
  Files         117      117              
  Lines       95189    95160      -29     
  Branches    95189    95160      -29     
==========================================
- Hits        85162    85160       -2     
+ Misses       7803     7775      -28     
- Partials     2224     2225       +1     

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[TheBlueMatt]

Does this work for your use-cases @tnull ?

[tnull]

Does this work for your use-cases @tnull ?

Ah, yes, nice code deduplication.

It also not only does work for lightningdevkit/ldk-node#244, but fixes a lifetime issue that was introduced with #2963 I had previously overlooked:

error: implementation of `Persist` is not general enough
   --> src/lib.rs:665:3
    |
665 | /         runtime.spawn(async move {
666 | |             process_events_async(
667 | |                 background_persister,
668 | |                 |e| background_event_handler.handle_event(e),
...   |
683 | |             });
684 | |         });
    | |__________^ implementation of `Persist` is not general enough
    |
    = note: `(dyn KVStore + std::marker::Send + std::marker::Sync + '0)` must implement `Persist<InMemorySigner>`, for any lifetime `'0`...
    = note: ...but `Persist<InMemorySigner>` is actually implemented for the type `(dyn KVStore + std::marker::Send + std::marker::Sync + 'static)`

error: could not compile `ldk-node` (lib) due to previous error

Would be great to land this for 0.0.122!

[TheBlueMatt]

Cool, LGTM. Taking @tnull's comment as a concept ACK and landing!