Message player on token action

[mvaessen]

Add option to send message to player along with SendTokens action

Discussed in #129

^{Originally posted by MrAtalon March 17, 2022}
Please add a message option to the token actions so that players know how much they have received. This most certainly helps with player engagement and retention.

[mvaessen]

Added one extra variable to the general variable replacer: {username} which gets replaced with the username of the account (steam user, epic user etc).

For this particular message field an extra variable is available: {amount} which shows the amount of tokens the player received