Shell: rewrite the whole shell to use tokens instead of raw strings

tab completion is still running with raw strings and that has to be
fixed in the future.

userspace/programs/Shell/Input.h

@@ -0,0 +1,36 @@
+#pragma once
+
+#include <BAN/NoCopyMove.h>
+#include <BAN/String.h>
+#include <BAN/Optional.h>
+#include <BAN/Vector.h>
+
+#include <sys/types.h>
+#include <termios.h>
+
+class Input
+{
+	BAN_NON_COPYABLE(Input);
+	BAN_NON_MOVABLE(Input);
+public:
+	Input();
+
+	BAN::Optional<BAN::String> get_input(BAN::Optional<BAN::StringView> custom_prompt);
+
+private:
+	BAN::String parse_ps1_prompt();
+
+private:
+	BAN::String m_hostname;
+
+	BAN::Vector<BAN::String> m_buffers { 1, ""_sv };
+	BAN::Vector<BAN::String> m_history;
+	size_t m_buffer_index { 0 };
+	size_t m_buffer_col { 0 };
+
+	BAN::Optional<ssize_t> m_tab_index;
+	BAN::Optional<BAN::Vector<BAN::String>> m_tab_completions;
+	size_t m_tab_completion_keep { 0 };
+
+	int m_waiting_utf8 { 0 };
+};