Feat(manual) - extension tool version

Description

Add home screen link to manual tool
Add list view to show interactive contents list of picsa steps
Add in-built pdf viewer and links to open contents on correct pdf page
Refactor activity page to display as alternate view (in future will be default for direct-to-farmer version)

Are the contents links sensible?
The pdf viewer is highly customisable. I've removed most functions to keep the screen simple (e.g. removed text search, print etc. but kept zoom, page change and contents sidebar). Are we happy with this approach?
The manual tool does not currently support translations as only the english version of the manual is bundled in the main build, but it is something we should consider adding support for. How best to do this will depend on whether we plan to keep translated pdfs within the main app, or have some other means of providing translations

Demo of manual tool Note - jerky zoom performance from video should now be fixed