commandblock: don't allow sending colored text if server forbids it

[fluxionary]

currently, players can get around the strip_color_codes setting by putting color escape sequences in a command block. this PR prevents that.

[SmallJoker]

I do not think that the use-case of strip_color_codes applies in this case. Command blocks are only triggered when there are people nearby, hence does not qualify as a regular chat command. Sending colors, such as in welcome messages or to improve readability should not be restricted.

[fluxionary]

Command blocks are only triggered when there are people nearby

sure, but the receiver doesn't have to be nearby, you can currently send messages to anyone on the server.

[SmallJoker]

Well ... that sucks

[Bastrabun]

For my reference 3922