deps(web-client): work around bug with @angular-devkit/build-angular …

…12.0.4+

@angular-devkit/build-angular 12.0.4+ makes build-storybook hang.

Constraining it to 12.0.3 avoids the hang.

Upstream issue, and workaround:

storybookjs/storybook#15227 (comment)

Also jump through some hoops to downgrade webpack from 5.39.1 to 5.38.1,
to match the exact dependency expected by @angular-devkit/build-angular,
and avoid this problem:

angular/angular-cli#20773

web-client/package.json

@@ -37,7 +37,7 @@
     "zone.js": "~0.11.4"
   },
   "devDependencies": {
-    "@angular-devkit/build-angular": "~12.0.1",
+    "@angular-devkit/build-angular": "~12.0.1 <12.0.4",
     "@angular-eslint/builder": "~12.0.0",
     "@angular-eslint/eslint-plugin": "~12.0.0",
     "@angular-eslint/eslint-plugin-template": "~12.0.0",