IBX-12173: Added Varnish 9 VCL

[vidarl]

🎫 Issue	IBX-12173

Caution

This PR cannot be merged up as-is as vcl files are different in here vs 5.0. Code for 5.0 is prepared in separate branch: IBX-12173_support_for_varnish9_50

Related PRs:

• IBX-12173: Added Varnish 9 Docker build docker#64 (consumes this file for the Docker build)
• IBX-12173: Added Varnish 9 support for Platform.sh/Upsun post-install#107 (consumes this file for Platform.sh/Upsun support)

Description:

Adds docs/varnish/vcl/varnish9.vcl for Varnish 9. VCL 4.1 syntax is unchanged between Varnish 7 and 9, so this file is
identical to varnish7.vcl apart from the header comment.

For QA:

Documentation:

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[konradoboza]

Thank you @vidarl! Side note: since 5.0 we most likely need that in https://github.com/ibexa/cloud/blob/5.0/resources/upsun/common/5.0/.platform/varnish.vcl too.

[bnowak]

Approved to ublock topic, based on it's 1:1 copy between versions.
I don't know vcl much, so if you want to have more confidence, please wait for some more reviewers 😉

[vidarl]

Thank you @vidarl! Side note: since 5.0 we most likely need that in https://github.com/ibexa/cloud/blob/5.0/resources/upsun/common/5.0/.platform/varnish.vcl too.

@konradoboza :PR created : ibexa/cloud#12
Talked to @barw4 and we think there is no need to merge up to 5.0 in ibexa/post-install as it is replaced by ibexa/cloud. Give me ping if you disagree