chore(rc,profile,aliases,completion,libs,functions): Remove shebangs from sourced files

These files are always sourced (never executed directly), so the
#!/bin/bash shebang is inert and misleading. Drop it consistently
across rc.d/*, profile.d/*, and aliases.d/*.

aliases.d/fun

@@ -1,5 +1,3 @@
-#!/bin/bash
-
 # Fun
 alias matrix='tr -c "[:digit:]" " " < /dev/urandom | dd cbs=$COLUMNS conv=unblock | GREP_COLOR="1;32" grep --color "[^ ]"'