Workspace template operator validation

[earaghbidikashani]

Remove Template Resolver After Webhook Migration

Current Status

Template resolver is still required for one remaining use case: applying environment variables from templates during deployment creation.
Webhook PR: #86

Blocker

The webhook's ApplyTemplateDefaults function handles most template fields but does not apply EnvironmentVariables from WorkspaceTemplate.spec.environmentVariables. The template resolver currently handles this
during deployment creation in the controller.

Prerequisites for Removal

1. Add EnvironmentVariables field to WorkspaceSpec:

   // EnvironmentVariables specifies environment variables for the workspace container
   // +optional
   EnvironmentVariables []corev1.EnvVar json:"environmentVariables,omitempty"

2. Update webhook to apply environment variables:

   if workspace.Spec.EnvironmentVariables == nil && len(template.Spec.EnvironmentVariables) > 0 {
       workspace.Spec.EnvironmentVariables = make([]corev1.EnvVar, len(template.Spec.EnvironmentVariables))
       copy(workspace.Spec.EnvironmentVariables, template.Spec.EnvironmentVariables)
   }

3. Update controller to use workspace spec directly instead of template resolver