Create a submodule to load GTM only after consent.

Patch works fine, the only thing I'm wondering about is the `data-src` attribute of the `

This breaks the loading of GTM when both usercentrics and simpleklaro are installed, but simple klaro is not enabled. Could we please add a check to ensure that Klaro is enabled and only then run the hooks?

The current version is not loading GTM on urls that are consisting of multiple slashes, e.g. example.com/x/y will try to load the script from https://www.example.com/x/modules/contrib/google_tag/js/gtm.js which is clearly the wrong path. The issue relies in how the data-src is created and is missing the leading slash so the links look like this in the DOM before being processed by klaro:

<script src="/?snv6li" type="text/plain" data-type="application/javascript" data-name="google-tag-manager" data-src="modules/contrib/google_tag/js/gtm.js"></script>

Next to not having the leading slash one can also see that the version query string is added to the src and not to the data-src attribute which is also wrong.

The updated MR results into the following script on the page:

<script type="text/plain" data-type="application/javascript" data-name="google-tag-manager" data-src="/modules/contrib/google_tag/js/gtm.js?snvjrf"></script>

I updated the submodule to version ^11.
I tested compatibility, and everything works without requiring any changes. Gtag loads correctly as soon as it’s selected in Klaro.

I just pushed a commit to respect the consent mode and if enabled always to load the gtag.js, as otherwise the gtag() function is not available for the Klaro callbacks and breaks the banner if used there.