Fix Assembly.Load with static constructors and fields

[josesimoes]

Description

• Rework code so that thread execution only continues after the static constructors are executed.
• Add PushValueU4 to CLR_RT_StackFrame.

Motivation and Context

• Fixes Static fields and static constructors aren't initialized/called when assembly is loaded in code Home#733.

How Has This Been Tested?

• Test project from the issue.

Screenshots

Types of changes

• Improvement (non-breaking change that improves a feature, code or algorithm)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Config and build (change in the configuration and build system, has no impact on code or features)
• Dependencies (update dependencies and changes associated, has no impact on code or features)
• Unit Tests (work on Unit Tests, has no impact on code or features)
• Documentation (changes or updates in the documentation, has no impact on code or features)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.