perf: save regular and Ledger wallets at once instead of dispatching multiple Vuex actions

[j-a-m-l]

Proposed changes

This PR revamps the wallet action of the Synchronizer service to save the fetched data of each wallet in 1 Vuex commit on the wallet store and 1 commit on the ledger store.

This has reduced the processing time from ~3000-6500ms to 500-2500ms, and it makes the UI less laggy.

Types of changes

• New feature (non-breaking change which adds functionality)
• Refactoring (improve a current implementation without adding a new feature or fixing a bug)
• Test (adding missing tests or fixing existing tests)

Checklist

• I have read the CONTRIBUTING documentation
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works

[codecov-io]

Codecov Report

Merging #1124 into develop will increase coverage by 0.1%.
The diff coverage is 73.8%.

@@            Coverage Diff             @@
##           develop    #1124     +/-   ##
==========================================
+ Coverage    40.96%   41.06%   +0.1%     
==========================================
  Files          215      215             
  Lines         5454     5481     +27     
  Branches      1067     1064      -3     
==========================================
+ Hits          2234     2251     +17     
- Misses        3096     3106     +10     
  Partials       124      124

Impacted Files	Coverage Δ
src/renderer/store/modules/wallet.js	45.78% <0%> (-6.28%)	⬇️
src/renderer/store/modules/ledger.js	74.75% <0%> (-1.11%)	⬇️
src/renderer/services/synchronizer/wallets.js	71.42% <87.32%> (+7.69%)	⬆️
src/renderer/components/Network/NetworkModal.vue	4.22% <0%> (ø)	⬆️

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