Allow using sst.wri.org instead of https://www.googletagmanager.com (gtm)

These need to be swappable with the url sst.wri.org in both places. We can use Content Snippets to accomplish this:

Dev tasks

[x] Add a new content snippet for Analytics URL and make its default value https://www.googletagmanager.com. I'm assuming in the rest of these instructions that the machine name is analytics_url
[x] Update https://github.com/wri/wri_sites/blob/main/themes/custom/ts_wrin/templates/layout/html.html.twig#L67 to use {{ contentSnippets.analytics_url }}
[x] Pass that code snippet to the wri_common javascript drupal settings in this function: https://github.com/wri/wri_sites/blob/main/modules/wri_common/wri_common.module#L522
[x] Modify https://github.com/wri/wri_sites/blob/main/modules/wri_common/js/wri_gtm.js to use a drupalSettings.wri_common.analytics_url

[x] An administrator can update the "Analytics URL" content snippet to use https://sst.wri.org/gtm.js instead of https://www.googletagmanager.com.
[x] When they do this they see a call to https://sst.wri.org/gtm.js in the "Sources" tab of the browser console.
[x] If you view the page's source, the code under the " Google Tag Manager (noscript)" section contains https://sst.wri.org/ not https://www.googletagmanager.com
[x] If the administrator has not updated the Analytics URL value, they should continue to see calls to https://www.googletagmanager.com in both tests above.

[ ] On https://develop-wriflagship.pantheonsite.io/ view source and confirm that there's an <iframe src="https://www.googletagmanager.com/ns.html?id=GTM-WGH5WB9" string.
[ ] On https://develop-wriflagship.pantheonsite.io/admin/content/content_snippets under "3rd Party" change the "Analytics URL" to https://sst.wri.org/
[ ] Review https://develop-wriflagship.pantheonsite.io/ again and verify the string is now `<iframe src="https://sst.wri.org/ns.html?id=GTM-WGH5WB9"
[ ] Verify that the https://sst.wri.org value is seeing analytics from the develop site.