[PM-2910] Add Account Switching Page (#6701)

* Collate browser header concerns into component

Header component has a slots field with a left, center, right, and a
right-most location for a current account, which will link to an account
switcher.

* Use feature flag if OK for production eventually

* Make sure centered content centered

* Allow for disabling header theming for login page

visual gitches exist for links and buttons, due to specifications futher down in the header, but those
items shouldn't use the `no-theme` option. For now, it's just for the
login screen

* Add Account Switching Component

* Collate browser header concerns into component

Header component has a slots field with a left, center, right, and a
right-most location for a current account, which will link to an account
switcher.

* Use feature flag if OK for production eventually

* Add Account Switching Component

* Fix Rebase Issues

* Remove Comments

* Move AccountSwitcher Logic Into Service

* Rename File

* Move Router to Component

* Add Tests for AccountSwitcherService

---------

Co-authored-by: Matt Gibson <mgibson@bitwarden.com>

apps/browser/src/popup/app-routing.module.ts

@@ -12,6 +12,7 @@ import { canAccessFeature } from "@bitwarden/angular/guard/feature-flag.guard";
 import { FeatureFlag } from "@bitwarden/common/enums/feature-flag.enum";
 
 import { fido2AuthGuard } from "../auth/guards/fido2-auth.guard";
+import { AccountSwitcherComponent } from "../auth/popup/account-switching/account-switcher.component";
 import { EnvironmentComponent } from "../auth/popup/environment.component";
 import { HintComponent } from "../auth/popup/hint.component";
 import { HomeComponent } from "../auth/popup/home.component";
@@ -362,6 +363,11 @@ const routes: Routes = [
       },
     ],
   },
+  {
+    path: "account-switcher",
+    component: AccountSwitcherComponent,
+    data: { state: "account-switcher" },
+  },
 ];
 
 @Injectable()