[Feature]: Set Discord Rich Presence to the game during scheduled matches and tournaments

[voyager-slama]

Is your feature request related to a problem?

When a scheduled MatchExec event starts, set the bot’s Discord Rich Presence to the event’s game (for example, Overwatch).

Describe the solution you'd like

This makes the bot’s activity reflect the event currently underway.

Additional context

This makes the bot’s activity reflect the event currently underway.

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Migrated from Todoist by voyager[bot].