fix(cdk/overlay): make it easier to set default for overlay directive

Adds the `CDK_CONNECTED_OVERLAY_DEFAULT_CONFIG` injection token to make it easier to configure the `CdkConnectedOverlay` directive.

(cherry picked from commit 41719c3)

Author: crisbeto

goldens/cdk/overlay/index.api.md

@@ -12,6 +12,7 @@ import { EmbeddedViewRef } from '@angular/core';
 import { EnvironmentInjector } from '@angular/core';
 import { EventEmitter } from '@angular/core';
 import * as i0 from '@angular/core';
+import { InjectionToken } from '@angular/core';
 import { Injector } from '@angular/core';
 import { Location as Location_2 } from '@angular/common';
 import { NgIterable } from '@angular/core';
@@ -37,6 +38,9 @@ export class BlockScrollStrategy implements ScrollStrategy {
     enable(): void;
 }
 
+// @public
+export const CDK_CONNECTED_OVERLAY_DEFAULT_CONFIG: InjectionToken<CdkConnectedOverlayConfig>;
+
 // @public
 export class CdkConnectedOverlay implements OnDestroy, OnChanges {
     constructor(...args: unknown[]);

src/cdk/overlay/overlay-directives.ts

@@ -96,6 +96,14 @@ export class CdkOverlayOrigin {
   constructor() {}
 }
 
+/**
+ * Injection token that can be used to configure the
+ * default options for the `CdkConnectedOverlay` directive.
+ */
+export const CDK_CONNECTED_OVERLAY_DEFAULT_CONFIG = new InjectionToken<CdkConnectedOverlayConfig>(
+  'cdk-connected-overlay-default-config',
+);
+
 /** Object used to configure the `CdkConnectedOverlay` directive. */
 export interface CdkConnectedOverlayConfig {
   origin?: CdkOverlayOrigin | FlexibleConnectedPositionStrategyOrigin;
@@ -283,9 +291,14 @@ export class CdkConnectedOverlay implements OnDestroy, OnChanges {
   constructor() {
     const templateRef = inject<TemplateRef<any>>(TemplateRef);
     const viewContainerRef = inject(ViewContainerRef);
+    const defaultConfig = inject(CDK_CONNECTED_OVERLAY_DEFAULT_CONFIG, {optional: true});
 
     this._templatePortal = new TemplatePortal(templateRef, viewContainerRef);
     this.scrollStrategy = this._scrollStrategyFactory();
+
+    if (defaultConfig) {
+      this._assignConfig(defaultConfig);
+    }
   }
 
   /** The associated overlay reference. */

src/cdk/overlay/public-api.ts

@@ -17,6 +17,7 @@ export {
   CdkOverlayOrigin,
   CdkConnectedOverlay,
   CdkConnectedOverlayConfig,
+  CDK_CONNECTED_OVERLAY_DEFAULT_CONFIG,
 } from './overlay-directives';
 export {FullscreenOverlayContainer} from './fullscreen-overlay-container';
 export {OverlayRef, OverlaySizeConfig} from './overlay-ref';