fix(provider): coalesce arch to armv7 if on 32-bit arm (#210)

This PR modifies the `coder_provisioner` datasource to return `arch` as `armv7` if `GOARCH=arm`.
This fixes an issue where users on 32-bit arm platforms would be unable to create a template with
```
resource "coder_agent" "main" {
  arch           = data.coder_provisioner.me.arch
  ...
}
```

and would instead need to manually specify

```
resource "coder_agent" "main" {
  arch           = "armv7"
  ...
}
```

Author: johnstcn

Diff for: docs/resources/agent_instance.md

@@ -3,7 +3,7 @@
 page_title: "coder_agent_instance Resource - terraform-provider-coder"
 subcategory: ""
 description: |-
-  Use this resource to associate an instance ID with an agent for zero-trust authentication. This association is done automatically for "googlecomputeinstance", "awsinstance", "azurermlinuxvirtualmachine", and "azurermwindowsvirtual_machine" resources.
+  Use this resource to associate an instance ID with an agent for zero-trust authentication. This association is done automatically for "google_compute_instance", "aws_instance", "azurerm_linux_virtual_machine", and "azurerm_windows_virtual_machine" resources.
 ---
 
 # coder_agent_instance (Resource)

Diff for: provider/provisioner.go

@@ -16,6 +16,10 @@ func provisionerDataSource() *schema.Resource {
 			rd.SetId(uuid.NewString())
 			rd.Set("os", runtime.GOOS)
 			rd.Set("arch", runtime.GOARCH)
+			// Fix for #11782: if we're on 32-bit ARM, set arch to armv7.
+			if runtime.GOARCH == "arm" {
+				rd.Set("arch", "armv7")
+			}
 
 			return nil
 		},

Diff for: provider/provisioner_test.go

@@ -31,9 +31,14 @@ func TestProvisioner(t *testing.T) {
 
 				attribs := resource.Primary.Attributes
 				require.Equal(t, runtime.GOOS, attribs["os"])
-				require.Equal(t, runtime.GOARCH, attribs["arch"])
+				if runtime.GOARCH == "arm" {
+					require.Equal(t, "armv7", attribs["arch"])
+				} else {
+					require.Equal(t, runtime.GOARCH, attribs["arch"])
+				}
 				return nil
 			},
 		}},
 	})
 }
+