Log process stdout/stderr by default

[matejchalk]

Context: #839 (comment)

Currently, executeProcess doesn't print stdout and stderr, but only returns the texts to the caller. If there is non-zero exit code and ignoreExitCode: true isn't set, then error is thrown with the stderr text in its message. Otherwise it is entirely up to the caller to print the process logs.

We could add a flag to toggle if process logs are printed, which would be less boilerplate than setting a custom observer object.
The question if logs should be printed by default or not. These logs would help with debugging, but could also be excessive in some cases.

• If logs should not be printed by default, then we can add a verbose flag.
• If logs should be printed by default, then we can add a silent flag (similarly to @actions/exec.
  • We could also connect executeProcess's silent flag with the CLI's --verbose option (silent: !verbose).

Acceptance critera

• analyze executeProcess in the codebase and decide if verbose or silent would be more appropriate (do we usually want to print logs or not?)
• implement new flag and update usage where appropriate