z/OSMF /info validation: implement retry mechanism and decouple from SAF authentication

[taban03]

Currently, the Launcher performs a mandatory validation of the z/OSMF /info endpoint during startup. We've observed couple of issues:

1. There is no retry logic for the /info call. A temporary network glitch or z/OSMF causes a permanent startup failure.
2. The validation is performed regardless of the authentication provider. If Zowe API ML is configured to use SAF, the availability of z/OSMF should not be a "hard" requirement for the API ML to start.

[Martin-Zeithaml]

The z/OSMF check is not mandatory, it can be either disabled or set to ignore any error:

zowe:
  launchScript:
    startupChecks:
      zosmf: "disabled"   # or "warn" to print possible error and continue

Another simple workaround is to delete/comment out zosmf configuration - the check is performed only if zosmf.host and zosmf.port are defined - in other words, if you have z/OSMF definition in your configuration, it is expected you need z/OSMF.

If the authentication provider is saf, generally Zowe is not z/OSMF independent - Zowe Desktop applications (like explorer-jes) requires z/OSMF.

Unfortunately there is a configuration gap we are not able to check (or I don't know how to):

• provider saf
• app-server enabled, but all explorers disabled - this looks like z/OSMF independent configuration, but
• Zowe Editor still requires z/OSMF for job submitting