Add validators functionality to prompts

[mpanchajanya]

What this PR does / why we need it

• Enable validations on prompts
• Implemented WithValidator() to set validator functions
• Added couple of custom validators NoUpperCase(), NoOnlySpaces()

Which issue(s) this PR fixes

Fixes #

Describe testing done for PR

• Added unit test to verify the changes including built in validators and custom validators
• Verified importing the tzr changes into tzc locally and tested tanzu context and tanzu login command with new validators required and NoOnlySpaces

Below testing show Required and no only spaces validators in action

mpanchajanya@mpanchajanF09MK ~/v/r/tanzu-cli (bug-fix-do-not-allow-empty-context-names)> tanzu context create
? Select context creation type Control plane endpoint
X Sorry, your reply was invalid: value contains only spaces
? Enter control plane endpoint test
X Sorry, your reply was invalid: value contains only spaces
? Give the context a name test
[i] Failed to test for vSphere supervisor: Get "test/wcp/loginbanner": unsupported protocol scheme ""
[x] : error creating kubeconfig with tanzu pinniped-auth login plugin: Get "test/wcp/loginbanner": unsupported protocol scheme ""
[x] : error creating kubeconfig with tanzu pinniped-auth login plugin: Get "test/wcp/loginbanner": unsupported protocol scheme ""
mpanchajanya@mpanchajanF09MK ~/v/r/tanzu-cli (bug-fix-do-not-allow-empty-context-names) [1]> tanzu context create
? Select context creation type Local kubeconfig
X Sorry, your reply was invalid: Value is required
? Enter path to kubeconfig (if any) test
X Sorry, your reply was invalid: Value is required
? Enter kube context to use test
X Sorry, your reply was invalid: Value is required
? Give the context a name test

Release note

prompt config accepts Validator functions to be performed on prompt answers

Additional information

Special notes for your reviewer

[anujc25]

LGTM