chore: remove deprecated global libraries

- `clipboard` => just use native `navigator.clipboard`
- `davclient.js` => use `webdav` or `@nextcloud/files`
- `moment` => use `@nextcloud/moment` or better native `Intl.DateTimeFormat` or `Temporal` API
- `underscore` => just use moder ES2015+ syntax

Adjusted core (remove usage of `_`) to be able to fully drop those
libraries as dependencies (except `moment` which we still use in some
legacy apps).

Now that `davclient.js` is gone we also can re-enable the
`Validate package-lock.json` step on CI.

Signed-off-by: Ferdinand Thiessen <opensource@fthiessen.de>

Author: susnux

.github/workflows/npm-build.yml

@@ -75,12 +75,11 @@ jobs:
       - name: Set up npm ${{ steps.versions.outputs.npmVersion }}
         run: npm i -g 'npm@${{ steps.versions.outputs.npmVersion }}'
 
-      # This does not work on server as we have some git dependencies that "npm-package-lock-add-resolved" cannot handle
-      # - name: Validate package-lock.json # See https://github.com/npm/cli/issues/4460
-      #   run: |
-      #     npm i -g npm-package-lock-add-resolved@1.1.4
-      #     npm-package-lock-add-resolved
-      #     git --no-pager diff --exit-code
+      - name: Validate package-lock.json # See https://github.com/npm/cli/issues/4460
+        run: |
+          npm i -g npm-package-lock-add-resolved@1.1.4
+          npm-package-lock-add-resolved
+          git --no-pager diff --exit-code
 
       - name: Install dependencies & build
         env: