BuildSystem: Cleanup userspace directory layout

userspace programs are now in userspace/programs
userspace tests are now in userspace/tests

This makes listing userspace projects much cleaner. Libraries were
already separated to their own directory, so other programs should also.

userspace/programs/Terminal/Terminal.h

@@ -0,0 +1,64 @@
+#pragma once
+
+#include <LibFont/Font.h>
+
+#include <LibGUI/Window.h>
+
+class Terminal
+{
+public:
+	void run();
+
+	uint32_t cols() const { return m_window->width() / m_font.width(); }
+	uint32_t rows() const { return m_window->height() / m_font.height(); }
+
+private:
+	void handle_csi(char ch);
+	void handle_sgr();
+	void putchar(uint32_t codepoint);
+	bool read_shell(int fd);
+
+	void on_key_event(LibGUI::EventPacket::KeyEvent);
+
+	void start_shell();
+
+private:
+	struct Cursor
+	{
+		uint32_t x;
+		uint32_t y;
+	};
+
+	struct ShellInfo
+	{
+		int in;
+		int out;
+		int err;
+		pid_t pid;
+	};
+
+	enum class State
+	{
+		Normal,
+		ESC,
+		CSI,
+	};
+
+	struct CSIInfo
+	{
+		int32_t fields[2];
+		size_t index;
+	};
+
+private:
+	BAN::UniqPtr<LibGUI::Window> m_window;
+	LibFont::Font m_font;
+	Cursor m_cursor { 0, 0 };
+	ShellInfo m_shell_info;
+	State m_state { State::Normal };
+	CSIInfo m_csi_info;
+
+	Cursor m_saved_cursor { 0, 0 };
+	uint32_t m_fg_color { 0xFFFFFF };
+	uint32_t m_bg_color { 0x000000 };
+};