Return HostStartSettings if local.settings.json is not loaded

[liliankasem]

Issue describing the changes in this PR

resolves #4604

Pull request checklist

• My changes do not require documentation changes
  • Otherwise: Documentation issue linked to PR
• My changes do not need to be backported to a previous version
  • Otherwise: Backport tracked by issue/PR #issue_or_pr
• My changes should not be added to the release notes for the next release
  • Otherwise: I've added my notes to release_notes.md
• I have added all required tests (Unit tests, E2E tests)

Additional information

This is an unfortunate overlap with how the help command is designed today, and how the start action's args use customer options.

Unfortunately the way that the help action is designed today makes it so that we need to load an action to get it's arguements/options. So in a situation like this where you run func to see the commands, we run the StartAction.ParseArgs -> which inits the secret manager to get host options (if any) -> secret manager looks for local.settings.json -> that doesn't exist outside of a func app dir -> exception.

This will all be reworked as part of our upcoming refactor, which will seperate these two things and cleanup the help command in general.

Updated GetHostStartSettings to catch the exception when local.settings.json does not exist and return a new HostStartSettings. If a customer configures these settings, then local.settings.json and/or host.json will exist and the exception won't occur. If a customer does not configure these settings, we use the default.