ISSUE-436: PDFJS 4.x + VTT Content Search API + Mirador 4.0 alpha 2 + ML

[DiegoPino]

See #436

• New ML supporting Code for Annotations + JS Triggers
• Newest PDF.js via module import/async (might need to pass the actual paths from PHP, but this also works)
• Theme level/template level accessibility and margins. Anyone can override the template
• New Option (simple/not so simple). Once I have the code the not so simple will enable native PDF.js search by using the pdfViewer class and the bus/dispatch/search controller. UPDATE: Or maybe I use the PDF Search Controller directly without the viewer. That would give me more control.
• Mirador 3.3.0 (default) and Mirador 4.0 alpha 2. (The former has CSS issues by the way, z-index)
• IIIF Content Search API with VTT and Plain Text (time/space mutation) processing + new settings
• JS improvements + small CSS
• New Twig template based Ajax/JS processors (data properties) for Views (on load/on click) and for Annotations (miniOCR) saved in Flavors with new Solr based Endpoint in our Annotations REST API

[DiegoPino]

@alliomeria Merging. Will keep working on the new issue/features in other branches, this one just became too huge. TODO:

• Document the new data-property (twig/html) driven Ajax/JS interactions. (for us too bc I will forget how this all works). I will make a pull request tomorrow AM + OpenAPI one too