refactor: strategy test start identities

[pauldelucia]

Issue being fixed or feature implemented

Strategy test start identities needed to be reset every strategy run before since the field was a vector of state transitions, and once the transition was added to the chain, it obviously couldn't be added again in a subsequent run. Changing it to a number which specifies how many start identities to create on the first block solves this issue.

What was done?

Change start_identities field in Strategy to a tuple of u8s, the first one specifying the number of identities to create and the second one the number of keys per identity. I did disable one test in rs-drive-abci strategy tests because it either doesn't work under this new design, or it will have to be heavily refactored. There is also a corresponding PR in rs-platform-explorer dashpay/platform-tui#27

How Has This Been Tested?

Strategy tests in Platform TUI and cargo test

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