Add flag to log the diagnostic events to stdout

[tsachiherman]

What

Add flag to quickstart image runtime params, to enable stdout printing of the soroban diagnostic events.

Acceptance Criteria:

• new flag, --log-soroban-diagnostic, should only be allowed when --enable-soroban-rpc is present
• identify design and implement capture stream of diagnostic events from the rpc server instance inside quickstart container.
  • option 1, start background shell, use js-soroban-client to establish an event stream listener and print to stdout.
  • option 2, run soroban events --start-ledger 0 ... as background command, redirect output to stdout
  • other approaches ?

Epic

stellar/stellar-cli#471