log signature after successful feature activation

[apfitzge]

Problem

When activating a feature the transaction Signature is not logged in the final result.
It is only logged temporarily in the progress bar during during transaction finalization.
If it activates quickly, The user misses the signature and has to find it manually.

Summary of Changes

Return the signature in the ProcessResult which is used to print final results.

Fixes #

[apfitzge]

Example of recent feature activation on testnet:

That trailing blank line is because the previous result was returning "".to_string().
With this change, the blank line would be filled with Signature: ...

[codecov]

Codecov Report

Merging #33488 (3a59417) into master (660e41a) will increase coverage by 0.0%.
Report is 36 commits behind head on master.
The diff coverage is 0.0%.

@@           Coverage Diff           @@
##           master   #33488   +/-   ##
=======================================
  Coverage    81.7%    81.7%           
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  Files         802      802           
  Lines      217786   217786           
=======================================
+ Hits       178082   178093   +11     
+ Misses      39704    39693   -11     

[brooksprumo]

Looks good to me. I'm going to add @CriesofCarrots as a reviewer to ensure someone that knows the whole CLI stuffs take a look for correctness/consistency/UX.

[CriesofCarrots]

There are actually a couple options here that would be more consistent with other parts of solana-cli, and automatically support --output json:

Suggested change

	let signature = rpc_client.send_and_confirm_transaction_with_spinner(&transaction)?;
	Ok(format!("Signature: {signature}"))
	let signature = rpc_client.send_and_confirm_transaction_with_spinner(&transaction)?;
	let signature = CliSignature {
	signature: signature.to_string(),
	};
	Ok(config.output_format.formatted_string(&signature))

This is also an option, and is cool because it adds nice parsing for instruction errors, but will need to be rewritten in the near future when we start using a bpf program for feature gate activations:

Suggested change

	let signature = rpc_client.send_and_confirm_transaction_with_spinner(&transaction)?;
	Ok(format!("Signature: {signature}"))
	let result = rpc_client.send_and_confirm_transaction_with_spinner(&transaction);
	log_instruction_custom_error::<SystemError>(result, config)

(PS. I've never tried putting two suggestions in one comment before. Hopefully it Just Works ™️ )