fix(sdk): dapi client pool should separate platform and core clients

[lklimek]

Issue being fixed or feature implemented

Connection pool should distinguish between Core and Platform connections

What was done?

Added prefix to key in connection pool, describing type of connection (Core or Platform) to use.

How Has This Been Tested?

Tested using rs-platform-explorer strategy tests against testnet.

Breaking Changes

None

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