refactor(@angular/cli): add ignorePeerDependencies option to package manager

This commit adds support for ignoring peer dependency warnings and errors during package installation. This is useful for commands like `ng update` where transient peer dependency conflicts may occur.

- Added `ignorePeerDependenciesFlag` to the `PackageManagerDescriptor` interface.
- Implemented the flag for `npm` (`--legacy-peer-deps`) and `pnpm` (`--strict-peer-dependencies=false`).
- Updated `PackageManager.install` to accept and apply the `ignorePeerDependencies` option.

Author: clydin

packages/angular/cli/src/package-managers/package-manager-descriptor.ts

@@ -62,6 +62,9 @@ export interface PackageManagerDescriptor {
   /** The flag to prevent lifecycle scripts from being executed. */
   readonly ignoreScriptsFlag: string;
 
+  /** The flag to ignore peer dependency warnings/errors. */
+  readonly ignorePeerDependenciesFlag?: string;
+
   /** A function that returns the arguments and environment variables to use a custom registry. */
   readonly getRegistryOptions?: (registry: string) => {
     args?: string[];
@@ -140,6 +143,7 @@ export const SUPPORTED_PACKAGE_MANAGERS = {
     saveDevFlag: '--save-dev',
     noLockfileFlag: '--no-package-lock',
     ignoreScriptsFlag: '--ignore-scripts',
+    ignorePeerDependenciesFlag: '--legacy-peer-deps',
     getRegistryOptions: (registry: string) => ({ args: ['--registry', registry] }),
     versionCommand: ['--version'],
     listDependenciesCommand: ['list', '--depth=0', '--json=true', '--all=true'],
@@ -215,6 +219,7 @@ export const SUPPORTED_PACKAGE_MANAGERS = {
     saveDevFlag: '--save-dev',
     noLockfileFlag: '--no-lockfile',
     ignoreScriptsFlag: '--ignore-scripts',
+    ignorePeerDependenciesFlag: '--strict-peer-dependencies=false',
     getRegistryOptions: (registry: string) => ({ args: ['--registry', registry] }),
     versionCommand: ['--version'],
     listDependenciesCommand: ['list', '--depth=0', '--json'],

packages/angular/cli/src/package-managers/package-manager.ts

@@ -308,11 +308,13 @@ export class PackageManager {
       force?: boolean;
       registry?: string;
       ignoreScripts?: boolean;
+      ignorePeerDependencies?: boolean;
     } = { ignoreScripts: true },
   ): Promise<void> {
     const flags = [
       options.force ? this.descriptor.forceFlag : '',
       options.ignoreScripts ? this.descriptor.ignoreScriptsFlag : '',
+      options.ignorePeerDependencies ? (this.descriptor.ignorePeerDependenciesFlag ?? '') : '',
     ].filter((flag) => flag);
     const args = [...this.descriptor.installCommand, ...flags];