fix: pass page context to readPageAnnotation for improved annotation handling

[luiso1979]

Fixes #288, resolves #290

This pull request introduces improvements to how PDF form field annotations are processed in the PdfiumEngine. The main updates involve capturing and exposing the "export value" for checkbox and radio button fields, and passing additional context when reading page annotations. These changes enhance the fidelity and utility of PDF annotation data in the engine.

PDF Form Field Annotation Enhancements:

• Added support for reading and returning the exportValue property for checkbox and radio button form fields, allowing consumers to access the value exported when the field is checked. [1] [2]
• Updated the PdfWidgetAnnoField interface to include an optional exportValue property, documenting its purpose and usage.

Annotation Reading Improvements:

• Modified the annotation reading logic to acquire and pass a page context (pageCtx) when reading page annotations, which may improve annotation handling and performance.

[vercel]

@luiso1979 is attempting to deploy a commit to the OpenBook Team on Vercel.

A member of the Team first needs to authorize it.

[luiso1979]

@bobsingor I just realized that I forgot to create a branch if it is a problem I can create one and resubmit the PR