wip(commands): re-implement core commands as bash functions

Re-implement all libexec executables as bash functions, with the goal of
being able build a single standalone execuable bash script for
tmuxifier.

lib/commands/resolve-command-path.sh

@@ -0,0 +1,43 @@
+# Resolve the absolute path to a tmuxifier command or alias.
+#
+# Usage:
+#   tmuxifier-resolve-command-path <command_or_alias>
+#
+# Arguments:
+#   $1 - Command name or alias to resolve
+#
+# Output:
+#   The absolute path to the command executable, or empty if not found.
+#
+# Returns:
+#   0 - Command was found
+#   1 - Command was not found
+tmuxifier-resolve-command-path() {
+  # Provide tmuxifier help
+  if calling-help "$@"; then
+    echo "usage: tmuxifier resolve-command-path <command_or_alias>
+
+Outputs the absolute path to the given command or command alias."
+    return
+  fi
+
+  local command_path=""
+
+  if [ -n "$1" ]; then
+    # Look for executable file, not functions.
+    command_path="$(type -P "tmuxifier-$1" 2> /dev/null)" || true
+    if [ -z "$command_path" ]; then
+      local resolved
+      resolved="$(tmuxifier-alias "$1")"
+      if [ -n "$resolved" ]; then
+        command_path="$(type -P "tmuxifier-$resolved" 2> /dev/null)" || true
+      fi
+    fi
+  fi
+
+  if [ -n "$command_path" ]; then
+    echo "$command_path"
+  else
+    return 1
+  fi
+}