Assorted Fixes #4

[manticore-projects]

1. Clickhouse global join

   • Replaces PR support clickhouse global keyword in join #1615
   • Fixes I use it to analyze clickhouse sql，But there is a problem，Can you show me #1535
   • All credits to @julianzlzhang, I just fixed the code style.

2. Support IF... ELSE... statements with Block()

   if (a=b) begin
   update table1 set a = 'xx' where b = 'condition1';
   update table1 set a = 'xx' where b = 'condition2';
   end;
   else begin
   update table1 set a = 'xx' where b = 'condition1';
   update table1 set a = 'xx' where b = 'condition2';
   end;

   • Fixes Some SQL server syntax does not support parsing #1682 / 1

3. Support SET statement with UserVariable

   set @Flag = 1

   • Fixes Some SQL server syntax does not support parsing #1682 / 2
   • Fixes Parsing "@@" throws exception #1237

4. Google Spanner Support
   Replaces PR Google Spanner support #1415, all credit goes to @s13o
   Re-arranged some recently added Tokens in alphabetical order
   Update Keywords

5. Amend JSONExpression and make it accept Expression beyond Column only

   SELECT '{"key": "value"}'::json -> 'key' AS X

   • Fixes PostgreSQL JSON arrow operators #1696