Epic: Completions for R

[DavisVaughan]

• [ ] https://github.com/posit-dev/positron/issues/1572 (Possibly its own thing, probably decent chunk of work)
• [ ] https://github.com/posit-dev/positron/issues/1514
• [x] https://github.com/posit-dev/positron/issues/1495
• [ ] https://github.com/posit-dev/positron/issues/550
• [ ] https://github.com/posit-dev/positron/issues/1612
• [ ] https://github.com/posit-dev/positron/issues/1818
• [ ] https://github.com/posit-dev/positron/issues/1830
• [ ] https://github.com/posit-dev/positron/issues/1828
• [ ] https://github.com/posit-dev/positron/issues/1615
• [ ] https://github.com/posit-dev/positron/issues/522
• [ ] https://github.com/posit-dev/positron/issues/1850
• [ ] Consider using a completions database that generates package completion information in a separate R session to avoiding loading the R package (To start, we could mock the separate R session part and just implement the database bit)
• [x] https://github.com/posit-dev/positron/issues/1871
• [ ] https://github.com/posit-dev/positron/issues/1872
• [ ] https://github.com/posit-dev/positron/issues/1873
• [x] https://github.com/posit-dev/positron/issues/2081
• [x] https://github.com/posit-dev/positron/issues/2221
• [ ] https://github.com/posit-dev/positron/issues/2417
• [ ] https://github.com/posit-dev/positron/issues/2574
• [ ] https://github.com/posit-dev/positron/issues/2676
• [ ] https://github.com/posit-dev/positron/issues/2936
• [ ] https://github.com/posit-dev/positron/issues/3002
• [x] https://github.com/posit-dev/positron/issues/3976

[DavisVaughan]

Done

• [x] https://github.com/posit-dev/positron/issues/1563
• [x] https://github.com/posit-dev/positron/issues/1352
• [x] https://github.com/posit-dev/positron/issues/1594
• [x] https://github.com/posit-dev/positron/issues/1648
• [x] https://github.com/posit-dev/positron/issues/1324
• [x] https://github.com/posit-dev/positron/issues/127
• [x] https://github.com/posit-dev/positron/issues/442
• [x] https://github.com/posit-dev/positron/issues/1452
• [x] https://github.com/posit-dev/positron/issues/1255
• [x] https://github.com/posit-dev/positron/issues/1331 (Possibly a Quarto bug)
• [x] https://github.com/posit-dev/positron/issues/1597
• [x] https://github.com/posit-dev/positron/issues/1735
• [x] Completions within a function signature should only show the argument names, and they should be in sequential order, not alphabetical order, if possible
• [x] For completions inside the () of a function, completions following $, and completions following @, we are going to need a way to "kill" any existing completions that have been added to the result set, because we might find that they aren't applicable (i.e. we don't want workspace completions to show up after a $). Also for file completions inside "".
• [x] https://github.com/posit-dev/positron/issues/1803