Adapt to the removal of the macros AST and to the new attachment upload API of XWiki 18.10

The XWiki 18.10 snapshots of the @xwiki/platform-* packages changed two APIs that Cristal relies on, and Cristal no longer builds against them:

• XWIKI-24402 removed the macros AST (MacroBlock, MacroInlineContent, ...) from @xwiki/platform-macros-api. Macros now render to the Block and InlineContent types of @xwiki/platform-uniast-api, which also gained rawHtml and macro editable-area nodes.
• XWIKI-24241 changed Storage.saveAttachments to return the uploaded attachments (PageAttachment) rather than their URLs.

Cristal's macro HTML rendering, the XWiki macros, the uniast HTML and BlockNote converters, and all the storages need to be adapted to these APIs.