Feature Description

Our plugins requires on things like libxml, DOMDocument, etc. to be available. Let's add some checks for these required features upon plugin initialization so that users know immediately when their server is not compatible.

The AMP plugin does this like so:

https://github.com/ampproject/amp-wp/blob/5f42cde04d84046e106fa9784d4cf2e61f3ba204/amp.php#L22-L154

We can refactor includes/namespace.php to have similar checks.

• Evaluate currently needed extensions, classes, and functions (likely libxml, DOMDocument)
• Evaluate needed extensions once Include AMP PHP Library #4513 is merged

Alternatives Considered

Additional Context

There have been some user reports where DOMDocument was not available, or libxml was outdated. Hence the requirement for this.

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Acceptance Criteria

Implementation Brief