feat(grid): Improve editor performance

[finger563]

Description

• Update grid c++ code to have editor-only function to detect property changes to width/height and reinitialize the grid cells accordingly
• Update grid cell to not have world position as member, but instead a GetWorldPosition() const method for calculating it from the grid - this ensures the grid cells do not need to be updated if the grid moves
• Update affected grid code to use new functions
• Update data stored for grids in the maps
• Update BP_Grid to not adjust grid in constructor
• Update BP_Grid to only fill attributes in beginplay

Motivation and Context

• Fixes a bug where BP_Grid did not properly set attributes for the cells
• Fixes performance in editor and switching between editor and PIE modes because grid could keep re-creating cells
• Fixes performance when editing grid class or grid objects (even just moving their positions)

How has this been tested?

PIE and ensuring the various grids in the prototype_blocking and playground maps work as expected w.r.t. grid cell ground type attributes / restrictions and ability to change their actor transforms.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• New Art / Asset
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update
• Art / Asset Update
• Software change

Checklist:

• My change requires a change to the documentation.
• I have added / updated the documentation related to this change via either README or WIKI

Software

• I have added tests to cover my changes.
• I have updated the .github/workflows/build.yml file to add my new test to the automated cloud build github action.
• All new and existing tests passed.
• My code follows the code style of this project.