fix(wpcarro/nix): Remove <briefcase> references

Angle-bracketed references are a Nix anti-pattern, and thankfully this
repository enforces this as a standard.

TL;DR:
- Drop angle-bracketed references
- Change `briefcase` -> `users.wpcarro`
- Fix any resulting regressions
- Fix //users/wpcarro/tools/simple_vim
- Mark //users/wpcarro/boilerplate/typescript and related projects
  as broken
- drop .skip-subtree file, enabling depot CI

Change-Id: I7153cbabafa617bfd6b199370cbec65cb75441f6
Reviewed-on: https://cl.tvl.fyi/c/depot/+/4325
Tested-by: BuildkiteCI
Reviewed-by: wpcarro <wpcarro@gmail.com>
Reviewed-by: tazjin <mail@tazj.in>
Reviewed-by: grfn <grfn@gws.fyi>
Autosubmit: wpcarro <wpcarro@gmail.com>

users/wpcarro/tools/monzo_ynab/main.go

@@ -10,7 +10,8 @@
 package main
 
 import (
-	"fmt"
+	"os"
+	"monzoSerde"
 )
 
 var (
@@ -34,7 +35,7 @@ func toYnab(tx monzoSerde.Transaction) ynabSerde.Transaction {
 
 func main() {
 	txs := monzo.TransactionsLast24Hours()
-	var ynabTxs []ynabSerde.Transaction{}
+	var ynabTxs []ynabSerde.Transaction
 	for tx := range txs {
 		append(ynabTxs, toYnab(tx))
 	}