wip: fish: Create personal port of Nord color theme

An official Nord port for the fish shell doesn't exist (i.e.,
nordtheme/nord#102), and the fish shell's
built-in Nord theme doesn't adhere to the color palette recommendations.
I'll use this until the official port exists to move over to.

fish/.config/fish/conf.d/theme.fish

@@ -0,0 +1,23 @@
+set -l nord0 2e3440
+set -l nord1 3b4252
+set -l nord2 434c5e
+set -l nord3 4c566a
+set -l nord4 d8dee9
+set -l nord5 e5e9f0
+set -l nord6 eceff4
+set -l nord7 8fbcbb
+set -l nord8 88c0d0
+set -l nord9 81a1c1
+set -l nord10 5e81ac
+set -l nord11 bf616a
+set -l nord12 d08770
+set -l nord13 ebcb8b
+set -l nord14 a3be8c
+set -l nord15 b48ead
+
+set -g fish_color_normal normal
+set -g fish_color_quote $nord14
+# TODO: Support optional italics for comments.
+set -g fish_color_comment $nord3 --italics
+set -g fish_color_escape $nord13
+set -g fish_color_autosuggestion $nord2