refactor: remove unused assets, move remaining assets out of payload packages (#12874)

This PR removes the `packages/payload/src/assets` folder for the
following reasons:
- they were published to npm. Removing this decreases the install size
of payload (excluding dependencies) from 6.22MB => 5.12MB
- most assets were unused. The only used ones were moved to a different
directory that does not get published to npm

This also updates some outdated asset URLs in our examples

.github/reproduction-guide.md

@@ -40,7 +40,7 @@ There are a couple ways run integration tests:
 
 - **Granularly** - you can run individual tests in vscode by installing the Jest Runner plugin and using that to run individual tests. Clicking the `debug` button will run the test in debug mode allowing you to set break points.
 
-  <img src="https://raw.githubusercontent.com/payloadcms/payload/main/packages/payload/src/assets/images/github/int-debug.png" />
+  <img src="https://raw.githubusercontent.com/payloadcms/payload/main/.github/assets/int-debug.png" />
 
 - **Manually** - you can run all int tests in the `/test/_community/int.spec.ts` file by running the following command:
 
@@ -57,7 +57,7 @@ The easiest way to run E2E tests is to install
 
 Once they are installed you can open the `testing` tab in vscode sidebar and drill down to the test you want to run, i.e. `/test/_community/e2e.spec.ts`
 
-<img src="https://raw.githubusercontent.com/payloadcms/payload/main/packages/payload/src/assets/images/github/e2e-debug.png" />
+<img src="https://raw.githubusercontent.com/payloadcms/payload/main/.github/assets/e2e-debug.png" />
 
 #### Notes