`INTERVAL '1 hour'` should be equivalent to `INTERVAL 1 HOUR`

**Use case**
People are used to Postgres.
"CROSS",
    "JOIN",
    "GLOBAL",
    "ANY",
    "ALL",
    "ASOF",
    "SEMI",
    "ANTI",
    "ONLY", 
    "ON",
    "USING",
    "PREWHERE",
    "WHERE",
    "GROUP",
    "WITH",
    "HAVING",
    "ORDER",
    "LIMIT",
    "OFFSET",
    "SETTINGS",
    "FORMAT",
    "UNION",
    "INTO",
    "NOT",
    "BETWEEN",
    "LIKE",
    "ILIKE",
    nullptr
};
bool ParserAlias::parseImpl(Pos & pos, ASTPtr & node, Expected & expected)