Relax Terraform provider version re-creation condition

[hugoShaka]

Fixes gravitational/teleport#39638

This PR keeps the mandatory version attribute but does not trigger re-creation when it changes like the v14 provider was doing. We might enable re-creation back in a future version.

Relaxing the re-creation is safe on any non-computed field. So basically every resource but the role with kubernetes_resource set.

This change is required because it's blocking people from upgrading to v15. I will investigate other fixes for the roles with Kubernetes resources attrs.

[wadells]

For context, I was encountering the error where upgrading an accesslist to v15 required adding version but that required addition was triggering a recreate. For resources like access lists that may be only partially terraformed this recreate is painful.

│ Error: Incorrect attribute value type
│ 
│   on access-lists.tf line 56, in resource "teleport_access_list" "access_list_reviewers":
│   56:   header = {
│   57:     metadata = {
│   58:       name = "${each.value.name}-reviewer"
│   59:     }
│   60:   }
│ 
│ Inappropriate value for attribute "header": attribute "version" is
│ required.

However, when I added the version (v1, pulled from tctl), I saw the access list s getting recreated.

# teleport_access_list.access_list["XYZ"] must be replaced
-/+ resource "teleport_access_list" "access_list" {
      ~ header = {
          ~ metadata = {
                name      = "XYZ"
              ~ namespace = "" -> (known after apply)
            }
          + version  = "v1" # forces replacement
        }
      ~ id     = "XYZ" -> (known after apply)
        # (1 unchanged attribute hidden)
    }

[wadells]

I don't know the code well enough to provide relevant feedback, but this has my approval in spirit.

[hugoShaka]

The tests are broken because of the relaxed condition. As this PR is already approved, I wrote a fix in another PR: #1043

[camscale]

Just a few wording changes, but otherwise LGTM.

[camscale]

s/re-render/re-renders/ or s/re-render/will re-render/

s/user provided/user-provided/

[camscale]

s/spec/allow/ in error message

[hugoShaka]

I spoke with @r0mant and we don't want to fix the role bug in v15 as this might be breaking for a small amount of users who already had roles upgraded from previous versions before reaching v15).

I will push the plan modifier in v16 and skip the broken test for now.