script: Initial stubs for Credential Management API (#38839)

Stubs `Credential`, `CredentialContainer`, and `PasswordCredential` and
adds the credentials attribute to navigator.

Testing: WPT
Fixes: Partially #38788

---------

Signed-off-by: Ashwin Naren <arihant2math@gmail.com>

components/script/dom/credentialmanagement/credentialscontainer.rs

@@ -0,0 +1,62 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+use std::rc::Rc;
+
+use dom_struct::dom_struct;
+use script_bindings::codegen::GenericBindings::CredentialsContainerBinding::{
+    CredentialCreationOptions, CredentialRequestOptions,
+};
+use script_bindings::error::{Error, Fallible};
+
+use crate::dom::bindings::codegen::Bindings::CredentialsContainerBinding::CredentialsContainerMethods;
+use crate::dom::bindings::codegen::DomTypeHolder::DomTypeHolder;
+use crate::dom::bindings::reflector::{Reflector, reflect_dom_object};
+use crate::dom::bindings::root::DomRoot;
+use crate::dom::credentialmanagement::credential::Credential;
+use crate::dom::globalscope::GlobalScope;
+use crate::dom::promise::Promise;
+use crate::script_runtime::CanGc;
+
+#[dom_struct]
+pub(crate) struct CredentialsContainer {
+    reflector_: Reflector,
+}
+
+impl CredentialsContainer {
+    pub(crate) fn new_inherited() -> CredentialsContainer {
+        CredentialsContainer {
+            reflector_: Reflector::new(),
+        }
+    }
+
+    pub(crate) fn new(global: &GlobalScope, can_gc: CanGc) -> DomRoot<CredentialsContainer> {
+        reflect_dom_object(
+            Box::new(CredentialsContainer::new_inherited()),
+            global,
+            can_gc,
+        )
+    }
+}
+
+impl CredentialsContainerMethods<DomTypeHolder> for CredentialsContainer {
+    // https://www.w3.org/TR/credential-management-1/#dom-credentialscontainer-get
+    fn Get(&self, _options: &CredentialRequestOptions<DomTypeHolder>) -> Fallible<Rc<Promise>> {
+        Err(Error::NotSupported)
+    }
+
+    // https://www.w3.org/TR/credential-management-1/#dom-credentialscontainer-store
+    fn Store(&self, _credential: &Credential) -> Fallible<Rc<Promise>> {
+        Err(Error::NotSupported)
+    }
+
+    // https://www.w3.org/TR/credential-management-1/#dom-credentialscontainer-create
+    fn Create(&self, _options: &CredentialCreationOptions<DomTypeHolder>) -> Fallible<Rc<Promise>> {
+        Err(Error::NotSupported)
+    }
+
+    // https://www.w3.org/TR/credential-management-1/#dom-credentialscontainer-preventsilentaccess
+    fn PreventSilentAccess(&self) -> Fallible<Rc<Promise>> {
+        Err(Error::NotSupported)
+    }
+}