feat: Create Simulator Test Framework with Fixtures

[mustafauzunn]

Reviewer Notes

Currently, we lack fixtures for the simulator, which limits our ability to write comprehensive tests.
Create a small testing initial framework with fixtures. With the effort here I aim mainly to introduce the fixtures, where in future ones we will refine it, according to needs.

• Create testFixtures in simulator
• Create TestBlockStreamManager in testFixtures to use getNextBlock
• Create BlockBuilder in testFixtures to handle block creation
• Move TestUtils to testFixtures
• Refactor some tests with TestBlockStreamManager and BlockBuilder
• Refactor some test mock configs with real configs

Related Issue(s)

Fixes #1333

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

@@             Coverage Diff              @@
##               main    #1393      +/-   ##
============================================
+ Coverage     80.93%   81.17%   +0.24%     
- Complexity      968      993      +25     
============================================
  Files           112      113       +1     
  Lines          4358     4457      +99     
  Branches        451      467      +16     
============================================
+ Hits           3527     3618      +91     
+ Misses          642      634       -8     
- Partials        189      205      +16     

see 18 files with indirect coverage changes

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