Unify MASP refs events

[grarco]

Describe your changes

Unifies the previous two masp refs events into a single MaspTxBatchRefs event: this ensures that no reordering of masp data can happen on the client side that would lead to the construction of an invalid state.

Updates the IndexedTx type to carry an optional pointer to a specific inner tx inside a batch. This fixes an issue for which the shielded sync command could not properly process multiple masp transactions in a same batch: it was appending the decrypted tx to a map using as an index the same block height and tx index, effectively taking into account only the last masp transaction of a batch

TODOs:

• See if there's a better way to emit the masp ref event (maybe without the need for ExtendedTxResult) (Reduce masp events #3824 )
• Update the indexer

Checklist before merging

• If this PR has some consensus breaking changes, I added the corresponding breaking:: labels
  • This will require 2 reviewers to approve the changes
• If this PR requires changes to the docs or specs, a corresponding PR is opened in the namada-docs repo
  • Relevant PR if applies:
• If this PR affects services such as namada-indexer or namada-masp-indexer, a corresponding PR is opened in that repo
  • Relevant PR if applies: Updates masp events namada-masp-indexer#21

[codecov]

Codecov Report

Attention: Patch coverage is 74.17582% with 47 lines in your changes missing coverage. Please review.

Project coverage is 72.80%. Comparing base (e603759) to head (561f604).
Report is 37 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/sdk/src/masp.rs	42.37%	34 Missing ⚠️
crates/sdk/src/masp/utilities.rs	80.00%	6 Missing ⚠️
crates/core/src/masp.rs	0.00%	3 Missing ⚠️
crates/node/src/protocol.rs	90.00%	1 Missing ⚠️
...hielded_token/src/masp/shielded_sync/dispatcher.rs	97.56%	1 Missing ⚠️
crates/shielded_token/src/masp/shielded_wallet.rs	95.45%	1 Missing ⚠️
crates/tx/src/types.rs	75.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3821      +/-   ##
==========================================
+ Coverage   72.79%   72.80%   +0.01%     
==========================================
  Files         338      338              
  Lines      103995   103989       -6     
==========================================
+ Hits        75701    75708       +7     
+ Misses      28294    28281      -13     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[brentstone]

Make an issue for better way to emit MASP ref event (in your TODO)?

[grarco]

Make an issue for better way to emit MASP ref event (in your TODO)?

Done with #3824