feat(platform)!: store/fetch genesis core height in misc tree

[ogabrielides]

Issue being fixed or feature implemented

Platform needs to know the genesis core height for correct credit pool calculations.

What was done?

Added fetch and store methods for the genesis core height in misc tree of groveDB.

How Has This Been Tested?

Breaking Changes

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated relevant unit/integration/functional/e2e tests
• I have added "!" to the title and described breaking changes in the corresponding section if my code contains any
• I have made corresponding changes to the documentation if needed

For repository code-owners and collaborators only

• I have assigned this pull request to a milestone

The base branch was changed.