static @NotNull Key key(@KeyPattern final @NotNull String string) {
    return key(string, DEFAULT_SEPARATOR);
  }
Creates a key.

<p>This will parse {@code string} as a key, using {@code :} as a separator between the namespace and the value.</p>

<p>The namespace is optional. If you do not provide one (for example, if you provide just {@code player} or {@code :player}
as the string) then {@link #MINECRAFT_NAMESPACE} will be used as a namespace and {@code string} will be used as the value,
removing the colon if necessary.</p>

@param string the string
@return the key
@throws InvalidKeyException if the namespace or value contains an invalid character
@since 4.0.0
key/src/main/java/net/kyori/adventure/key/Key.java