Expose clear transients in ecctl

Description

Exposes new clear_transients field for ecctl for show deployment.

The default value depends on on the value of generate-update-payload in order to facilitate safe usage of the "read - edit - write" loop. If generate-update-payload=true then clear-transients also defaults to true and is false otherwise. If the flag is manually passed then that value takes precedence.

Motivation and Context

This change makes reading and writing deployments safer. We ran into this during the last security remediation and almost overwrote someone’s cluster from their most recent snapsho

How Has This Been Tested?

This has been tested by using local build to operate against QA ESS. I have verified that with --generate-update-payload=true the transient properties are not included (default behavior). If --generate-update-payload=true and --clear-transient=false is explicitly passed then transient properties are included.

Types of Changes

[ ] Bug fix (non-breaking change which fixes an issue)
[x] New feature (non-breaking change which adds functionality)
[ ] Refactoring (improves code quality but has no user-facing effect)
[ ] Breaking change (fix or feature that would cause existing functionality to change)
[ ] Documentation

Readiness Checklist

[x] My code follows the code style of this project
[x] My change requires a change to the documentation
[x] I have updated the documentation accordingly
[x] have added tests to cover my changes
[x] All new and existing tests passed

elastic / ecctl