feat(third_party/gopkgs): add charmbracelet/{bubbletea,bubbles}

A small go TUI framework based on the Elm Architecture.

Change-Id: I0c400a7b25af682735bfc5061db179e5d1dd75ab
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2853
Reviewed-by: Profpatsch <mail@profpatsch.de>
Reviewed-by: lukegb <lukegb@tvl.fyi>
Tested-by: BuildkiteCI

third_party/gopkgs/github.com/muesli/reflow/default.nix

@@ -0,0 +1,16 @@
+{ depot, pkgs, ... }:
+
+depot.nix.buildGo.external {
+  path = "github.com/muesli/reflow";
+  src = pkgs.fetchFromGitHub {
+    owner = "muesli";
+    repo = "reflow";
+    # unreleased version required by bubbletea
+    rev = "9e1d0d53df68baf262851201166872afafd04e5d";
+    sha256 = "08bmkqdn7sb5laqc1mvgk4xj31f600n1y04s1ifppjvszbcsxhid";
+  };
+
+  deps = with depot.third_party; [
+    gopkgs."github.com".mattn.go-runewidth
+  ];
+}