feat(site): connect open_in parameter (#16036)

Second step to resolve [open_in
issue](https://github.com/coder/terraform-provider-coder/issues/297)

This PR improves the way the open_in parameter is forwarded across the
code, changing the last `string` to const everywhere.

Also make sure it is available and forwarded up to the `CreateLink`
component.

codersdk/workspaceapps.go

@@ -28,6 +28,12 @@ const (
 	WorkspaceAppSharingLevelPublic        WorkspaceAppSharingLevel = "public"
 )
 
+var MapWorkspaceAppSharingLevels = map[WorkspaceAppSharingLevel]struct{}{
+	WorkspaceAppSharingLevelOwner:         {},
+	WorkspaceAppSharingLevelAuthenticated: {},
+	WorkspaceAppSharingLevelPublic:        {},
+}
+
 type WorkspaceAppOpenIn string
 
 const (
@@ -36,10 +42,10 @@ const (
 	WorkspaceAppOpenInTab        WorkspaceAppOpenIn = "tab"
 )
 
-var MapWorkspaceAppSharingLevels = map[WorkspaceAppSharingLevel]struct{}{
-	WorkspaceAppSharingLevelOwner:         {},
-	WorkspaceAppSharingLevelAuthenticated: {},
-	WorkspaceAppSharingLevelPublic:        {},
+var MapWorkspaceAppOpenIns = map[WorkspaceAppOpenIn]struct{}{
+	WorkspaceAppOpenInSlimWindow: {},
+	WorkspaceAppOpenInWindow:     {},
+	WorkspaceAppOpenInTab:        {},
 }
 
 type WorkspaceApp struct {
@@ -70,7 +76,7 @@ type WorkspaceApp struct {
 	Healthcheck Healthcheck        `json:"healthcheck"`
 	Health      WorkspaceAppHealth `json:"health"`
 	Hidden      bool               `json:"hidden"`
-	OpenIn      string             `json:"open_in"`
+	OpenIn      WorkspaceAppOpenIn `json:"open_in"`
 }
 
 type Healthcheck struct {