mail: Add mail- prefix to mail cli utilities

Rename mail utility programs (yet again), to be prefixed with `mail-`
instead of `neomutt-`. Also did not substitute with other MUA like
`aerc-` since these utilities are mostly independent of specific
implementations.

The very specific `neomutt-filer` implementation script I completely
removed since for aerc the same can be achieved with a simple
configuration option.

office/.local/bin/mail-renderhtml

@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+# render html as markdown and display in glow, supports syntax highlighting
+# requires: html2text, glow or bat
+# author: CEUK
+
+fpath=$(mktemp --suffix=-mail-render.html)
+
+#shellcheck disable=SC2064 # we want to expand it instantly
+trap "rm -f -- ${fpath@Q}" EXIT
+
+perl -0777pe 's/(<code class="sourceCode\s?)(\w+?)(">)(.*?)(<\/code>)/\1\2\3\n```\2\n\4\n```\n\5/gs' "$1" | html2text | sed -re 's/^\s+(```(\w+)?)/\1/gm' -e 's/\x1b\[[6-9;]*m//g' >"$fpath"
+
+if command -v bat >/dev/null 2>&1; then
+    bat "$fpath"
+elif command -v glow >/dev/null 2>&1; then
+    glow -s ~/.config/glow/email.json "$fpath"
+else
+    sed 's/\x1b\[[6-9;]*m//g' <"$fpath"
+fi