#128 and #125: RAG Improvements

[zateutsch]

fixes #125
fixes #128

Summary of changes:

• Removed RAG indexing progress indicator as it wasn't updating the UI properly, only takes 5-10 seconds, and complicates the sample to have it in there
• Added a "Select PDF" button to the prompting view to allow users to select a new PDF without reloading the sample
• Moved key functions up in the source so that viewing the code shows you IndexPDF() and DoRAG() towards the top of the file.

[nmetulev]

On my machine, I indexed war and piece and it took a minute to index. Without the progress tracking, I wasn't sure if the sample is working. I think we need some progress tracking in there - can you think of a way to add it that works?

[nmetulev]

Also, the close button on the pdf overlaps the select pdf button

[nmetulev]

left comments on the pr

[niels9001]

Thought: should we have the PDF reader thing inline with the text so it's side-by-side?

Something like this, but then with clickable page numbers to navigate to the pages?

[nmetulev]

@niels9001, should we block this PR on adding the side by side, or can we add it another time?

[niels9001]

@niels9001, should we block this PR on adding the side by side, or can we add it another time?

No let's get this in, we can add it later.