Add blueprint validation logic to deferPhases as well

[viveksinghggits]

Change Overview

Blueprint validation logic needed to be changed for deferPhase that we introduces as part of the base branch.

Pull request type

Please check the type of change your PR introduces:

• 🚧 Work in Progress
• 🌈 Refactoring (no functional changes, no api changes)
• 🐹 Trivial/Minor
• 🐛 Bugfix
• 🌻 Feature
• 🗺️ Documentation
• 🤖 Test

Issues

• DeferPhase is not being validated via blueprint validating webhook  #1360

Test Plan

• ⚡ Unit test

~/work/opensource/kanister/pkg/blueprint/validate (deferphase-validate*) » go test 
Failed the 'validation of phase 00 in action backup' check.. ❌
Passed the 'validation of phase 10 in action backup' check.. ✅
Passed the 'validation of phase 11 in action backup' check.. ✅
Failed the 'validation of action backup' check.. ❌
Passed the 'validation of phase 30 in action backup' check.. ✅
Failed the 'validation of phase 40 in action backup' check.. ❌
Failed the 'validation of phase 51 in action backup' check.. ❌
Failed the 'validation of phase 61 in action backup' check.. ❌
Passed the 'validation of phase 71 in action backup' check.. ✅
Passed the 'validation of phase 70 in action backup' check.. ✅
OK: 1 passed
PASS
ok  	github.com/kanisterio/kanister/pkg/blueprint/validate	0.019s

[pavannd1]

LGTM