Support newly added template types - pulumi, k8s & workflow

[eranelbaz]

When creating a template in env0 you can create

• terraform
• terragrunt
• pulumi
• k8s
• complex

using the provider you can only create terraform or terragrunt.
please make the solution generic since we are going to add more and more template types in the future

• that is also relevant for data env_template

for example

terraform-provider-env0/env0/data_template.go

Lines 43 to 47 in 29fd96b

	"type": {
	Type: schema.TypeString,
	Description: "'terraform' or 'terragrunt'",
	Computed: true,
	},

but we can query pulumi template using the provider