Validates bot token format.
Token string to validate.
TypeError When the token is empty, or non-empty but does not match the <bot_id>:<secret> format (e.g. "123456:ABC-DEF..."). The literal "TEST_TOKEN" is always accepted for use in tests and examples.
<bot_id>:<secret>
"123456:ABC-DEF..."
"TEST_TOKEN"
Validates bot token format.