Transform website to a book

[eldobbins]

Fixes #44

This PR makes these changes:

• changes the content of _quarto.yml to the book syntax. (The original website code is stashed in a separate backup file.
• adds section cross references and uses those instead of HTML links
• adds table cross references. Note: doing this for the historic reports table wouldn't work with the insert set-up so I copied the table into historic_reports.qmd
• Change some header levels so they would not get section numbers appended. Book looked "too busy" otherwise
• Changed the figure margins to eliminate excessive space around the tables. I did experiment with centering figures and made notes in #42. Spoiler: I could not center figures generated by Observable.

[jikaczmarski]

This looks phenomenal. My only request would be to change the following section titles:

• Alaska Generation Capacity -> Installed Capacity
• Alaska Electricity Generation -> Net/Gross Generation
• Electricity Consumption -> Consumption and Sales

[ianalexmac]

Great work! We've heard from a number of researchers who would like straightforward access to the data. Perhaps we could move the "Data Portal" link in the sidebar down to the bottom of the sidebar so it pops a little more?