RFE: meaningful default name to save the preflights checks

[camilamacedo86]

Describe the rationale for the suggested feature.

After run kubectl preflight https://preflight.replicated.com and choose the s option to save the default output seems to be "o". Could we change that for for example preflight_checks.txt or preflight_checks_.txt?

[chris-sanders]

lol, I think "o" is a pretty strange default surly we can do better than that.

[xavpaice]

This appears to be the same for support-bundle - however in preflight, the help for the flag is in ./pkg/preflight/flags.go, and in support-bundle it's in ./cmd/troubleshoot/cli/root.go. I don't see at first look where the default is set for preflight.

Definition of done:

• if -o is specified for either preflight or support-bundle, without supplying a filename, the output filename should be named preflight.tar.gz or support-bundle.tar.gz
• if you run preflight or support-bundle interactively and opt to save the file, the output filename should be named preflight.tar.gz or support-bundle.tar.gz

[DexterYan]

By looking at two previous PRs #769 and #538, seems the default logic was:

• if -o is not specified for preflight, the output filename should be named
  <preflight name>-results-<date>.txt
• if -o is specified for preflight, without supplying a filename, there will be an error which is
  Error: flag needs an argument: 'o' in -o
• if -o is specified for preflight, with supplying a filename, the output filename should be the same as cli input

And for kubectl preflight https://preflight.replicated.com, the default output file name will be example-results-2022-11-14T14_54_14.txt

For the current issue, it is possible that we are not using the flags.StringVarP function to migrate the previous cmd.Flags().StringP("output", "o", "", "***"). I will make a pr for that.