feat(config): ui width, auto exec, selection and navigation configs (#80)

closes #67

So I made an auto-exec confg `auto-exec = true`
(e32c0ba6ed69f3c764353e58b8fbacf160f37d5a) which means:
- If you want your command in the prompt to be executed right away, you
can set this = false (for example, you are typing `nvim ~/.conf` but
IRIS is suggesting `nvim ~/.config`, it will ignore the suggestion and
exec what you are typing, this is current default behavior)
- If you want to auto execute full command which is being suggested, you
can set this = true (this is the opposite of above, when you are typing
`nvim ~/.conf` but IRIS is suggesting `nvim ~/.config`, it will auto
exec `nvim ~/.config` instead, but sometime you want to exec what you
are typing instead of the suggestion right?, just press esc or shift tab
to hide the menu and it will)

---

Select keybinding to replace tab
(0dc01cba8c610e8d6fd8c50f6a71bdcc061a098f)
`select = "ctrl+y"`

Some users may love nvim keybinding or emacs, so I bring navigation
keybinding to be configurable (0dc01cba8c610e8d6fd8c50f6a71bdcc061a098f)
```
navigate-up = "ctrl+k"
navigate-down = "ctrl+j"
```
---

I also added a option for UI width
(dfa3b810a7be406fe4652b3886020f37bb166811)
`max-width = 80`
- If you configure `max-width` to be larger than the actual width of the
current terminal, Iris will automatically "compress" the window to match
the terminal's width (meaning it will never overflow and break the
interface)
- If you configure `max-width` too small (e.g 10), the interface will
have cramped text, making it look very bad. So, I've set a minimum safe
min limit of 40. If the configured value is smaller than this, Iris will
automatically use 40

Small note: If you set `max-width = 0` (or leave it blank), it will
automatically use Iris's default standard size of 76. SO you can
confidently customize it without fear of breaking the UI (I hope so
lmao)

---

Added a fallback to ensure Iris never crashes or loses shortcuts if the
user accidentally deletes keybinding configuration lines or
intentionally assigns empty strings " "
(f682c9bf623f3ed46ad0763221145604dbd91b07)

Fix typo `toggle_mode` to `toggle-mode`
(b39be6673e552735fa65a6c9807510c83b4d9cdd)

if you have a better config design, please tell me, I always listen to
your idea

internal/config/keys.go

@@ -13,6 +13,8 @@ func MatchKey(input []byte, expected string) (matched bool, consumed int) {
 	}
 
 	expected = strings.ToLower(strings.TrimSpace(expected))
+	expected = strings.TrimPrefix(expected, "<")
+	expected = strings.TrimSuffix(expected, ">")
 
 	if strings.HasPrefix(expected, "ctrl+") && len(expected) == 6 {
 		char := expected[5]
@@ -38,12 +40,24 @@ func MatchKey(input []byte, expected string) (matched bool, consumed int) {
 		if len(input) >= 3 && input[0] == 0x1b && input[1] == '[' && input[2] == 'Z' {
 			return true, 3
 		}
+	case "up":
+		if len(input) >= 3 && input[0] == 0x1b && (input[1] == '[' || input[1] == 'O') && input[2] == 'A' {
+			return true, 3
+		}
+	case "down":
+		if len(input) >= 3 && input[0] == 0x1b && (input[1] == '[' || input[1] == 'O') && input[2] == 'B' {
+			return true, 3
+		}
 	case "right":
 		// typically \033[C or \033OC
 		if len(input) >= 3 && input[0] == 0x1b && (input[1] == '[' || input[1] == 'O') && input[2] == 'C' {
 			return true, 3
 		}
-	case "enter":
+	case "left":
+		if len(input) >= 3 && input[0] == 0x1b && (input[1] == '[' || input[1] == 'O') && input[2] == 'D' {
+			return true, 3
+		}
+	case "enter", "cr", "return":
 		if input[0] == 0x0d || input[0] == 0x0a {
 			return true, 1
 		}