[Redshift] Support double casting inside function

[tobiasheldring]

Describe the bug
Double cast parses fine, but not inside a function eg. a COUNT. then it gives the error below

 SyntaxError: Expected "!=", "!~", "!~*", "#-", "#>", "#>>", "%", "&&", "(", ")", "*", "+", ",", "-", "--", "->", "->>", "/", "/*", "<", "<=", "<>", "<@", "=", ">", ">=", "?", "?&", "?|", "@>", "AND", "AS", "BETWEEN", "ILIKE", "IN", "IS", "LIKE", "NOT", "OR", "ORDER", "SIMILAR", "\"", "||", "~", "~*", [ \t\n\r], or [A-Za-z_一-龥] but ":" found.

Database Engine
Redshift

To Reproduce
Add the following test case to redshift.spec.js

it('should support double cast inside count', () => {
    const sql = "SELECT COUNT(DISTINCT event_time::DATE::TEXT || '_' || event_type) FROM my_events"
    expect(getParsedSql(sql)).to.be.equal("SELECT COUNT(DISTINCT event_time::DATE::TEXT || '_' || event_type) FROM my_events")
  })