Add the opentelemetry extension and SVG support in Imagick

[mistraloz]

Summary

This PR implements :

• Bug
• Feature
• Breaking changes

Two extension requests that are cheap to support:

• opentelemetry (Extension opentelemetry #384) is now available on PHP 8.2+, from the Ondřej PPA package. It is disabled by default, like the other optional extensions.
• Imagick can read SVG (Imagick doesn't support SVG #393). The extra ImageMagick coders are installed with the extension, which also brings WMF, DjVu and OpenEXR, for about 17 MB on the fat images. Remote resources stay blocked by the Ubuntu ImageMagick policy, and the README explains how to restrict the formats when processing untrusted images.

Closes #384
Closes #393

Test plan (required)

The build already checks that each extension loads. php-extensions.sh now also checks opentelemetry and SVG support in Imagick; it passes on PHP 8.2 to 8.5:

TAG_PREFIX=pr-ext- docker buildx bake --load php84-slim-cli php84-cli
TAG_PREFIX=pr-ext- PHP_VERSION=8.4 BRANCH=v5 VARIANT=cli ./tests-suite/bash_unit -f tap ./tests-suite/php-extensions.sh

Checklist

• I followed the guidelines in CONTRIBUTING guide
• I have squashed any insignificant commits
• This change has comments for package types, values, functions, and non-obvious lines of code