Improve speculative shielded ctx

[grarco]

Describe your changes

Closes #3457.
Closes #2593.

Moved the transition to the SpeculativeContext from the SDK to the client to have access to the (possible) tx result. The transition is now performed when:

• the submitted transaction is successfully applied
• the transaction is broadcasted
• the transaction is dumped to storage

The transition is not performed when:

• the transaction gets dry-run
• the transaction is loaded from storage

Added an integration test to verify the behavior of the client when in a speculative context.

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:

[batconjurer]

Apart from sug0's requested changes, this looks fine

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 73.91%. Comparing base (b2332bf) to head (33dd44f).
Report is 87 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4019      +/-   ##
==========================================
- Coverage   73.92%   73.91%   -0.01%     
==========================================
  Files         341      341              
  Lines      106510   106496      -14     
==========================================
- Hits        78740    78720      -20     
- Misses      27770    27776       +6     

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

---

🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests

[sug0]

couple of nits but otherwise lgtm