PLT-5764 Fixed channel name minimum length (#5693)

* make sure that we use constants for channel name min length

* changed channel name error to match channel URL error

* changed constant max channel name length to 22 and reapply in modal

* reverted dutch translation

webapp/utils/constants.jsx

@@ -868,6 +868,8 @@ export const Constants = {
     DEFAULT_MAX_NOTIFICATIONS_PER_CHANNEL: 1000,
     MAX_TEAMNAME_LENGTH: 15,
     MAX_TEAMDESCRIPTION_LENGTH: 50,
+    MIN_CHANNELNAME_LENGTH: 2,
+    MAX_CHANNELNAME_LENGTH: 22,
     MIN_USERNAME_LENGTH: 3,
     MAX_USERNAME_LENGTH: 22,
     MAX_NICKNAME_LENGTH: 22,