refactor(platform-server): import xhr2 dynamically in the ServerXhr…

… class (#50095)

This commit updates the `@angular/common/http` and `@angular/platform-server` packages to allow dynamic import of the `xhr2` dependency. The `xhr2` dependency has side-effects that rely on a global scope and as a result in some environments those side-effectful calls fail. With the changes from this PR, the import is delayed until it's actually needed, which gives a chance for the underlying platform to setup global scope (via shims) as needed.

Co-authored-by: alan-agius4 <17563226+alan-agius4@users.noreply.github.com>

PR Close #50095

integration/platform-server/angular.json

@@ -116,6 +116,7 @@
               "outputHashing": "media"
             },
             "development": {
+              "buildOptimizer": false,
               "optimization": false,
               "sourceMap": true,
               "extractLicenses": false,
@@ -239,6 +240,7 @@
               "outputHashing": "media"
             },
             "development": {
+              "buildOptimizer": false,
               "optimization": false,
               "sourceMap": true,
               "extractLicenses": false,