fix: SequenceDiagram: draw activations even without explicit deactivation

[dansseg]

📑 Summary

Activations will now also be drawn, even if there is no deactivation for a participant. The activation will reach down to the bottom or to the point where the participant gets destroyed.

sequenceDiagram
    A ->>+ B : ActivateMe
    B ->> A : NoNeedToDeactivate

Resolves #3849

📏 Design Decisions

All activations were already parsed correctly and stored in 'bounds.activations'. If no deactivation was existing, it would remain inside this array. This information is now used to draw the 'missing' activations after all actors and messages were drawn already.
If an actor was destroyed, it's last y position is also stored already (bounds.models.actors[].stopy), which will then be used as the end of the activation, instead of the end of the diagram.

📋 Tasks

Make sure you

• 📖 have read the contribution guidelines
• 💻 have added necessary unit/e2e tests.
• 📓 have added documentation. Make sure MERMAID_RELEASE_VERSION is used for all new features.
• 🔖 targeted develop branch

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[codecov]

Codecov Report

Attention: Patch coverage is 0% with 17 lines in your changes are missing coverage. Please review.

Project coverage is 5.72%. Comparing base (3809732) to head (2b9d052).

Additional details and impacted files

@@            Coverage Diff             @@
##           develop   #5457      +/-   ##
==========================================
- Coverage     5.72%   5.72%   -0.01%     
==========================================
  Files          278     277       -1     
  Lines        42013   42019       +6     
  Branches       490     515      +25     
==========================================
  Hits          2407    2407              
- Misses       39606   39612       +6     

Flag	Coverage Δ
unit	5.72% <0.00%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
.../mermaid/src/diagrams/sequence/sequenceRenderer.ts	0.00% <0.00%> (ø)

... and 1 file with indirect coverage changes

[sidharthv96]

Hi @dansseg, can you please add integration tests to cover all the cases that you are expecting this to fix?
The implementation seems to be working for some cases I tested.

File: cypress/integration/rendering/sequencediagram.spec.js