fix(sdk)!: mock sdk cannot find quorum keys in offline mode

[lklimek]

Issue being fixed or feature implemented

In some circumstances, mocking subsystem fails to load public keys from test vectors directory.

What was done?

Mock SDK uses "main" Sdk object's MockContextProvider to fetch quorum info.
Fixed configuration of MockContextProvider and mock sdk to autoload vectors on start.

How Has This Been Tested?

Using GHA

Breaking Changes

It is no longer needed to load test vectors or quorum keys, as they are automatically loaded from the dump_dir during SdkBuilder::build().

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