Check bonding state before activating orchestrator in CLI

[Lazydayz137]

What does this pull request do?

Adds a pre-flight check that queries on-chain bonding state before the bond transaction, returning a clear error instead of the misleading "ERC20: transfer amount exceeds balance" message.

Specific updates

• Query GetDelegator before bond transaction in activateOrchestratorHandler
• Return 400 with actionable message if wallet is bonded to a different address
• Handle nil delegator and nil BondedAmount defensively
• Add GetDelegator mock expectation to TestActivateOrchestratorHandler_Success

How did you test each of these updates?

• go test ./server/... passes
• go vet ./server/... clean
• gofmt clean

Does this pull request close any open issues?

Fixes #2643

Checklist

• I have read the contribution guide
• make and tests run successfully
• Code is formatted with gofmt