Add the support of CREATE FUNCTION

[orginux]

file create-function.sql:

CREATE FUNCTION linear_equation AS (x, k, b) -> k*x + b;

clickhouse-sql-parser -format -f  create-function.sql

output:

panic: parse statements error: line 0:7 <EOF> or ';' was expected, but got: "FUNCTION"
CREATE FUNCTION linear_equation AS (x, k, b) -> k*x + b;
       ^^^^^^^^

UDF in ClickHouse documentation

[git-hulk]

Hi @orginux Thanks for your feedback!

It's right we now don't support creating UDF, I will submit a patch for this later.

[orginux]

Great, thanks a lot @git-hulk