Support dialect-specific auto-increment column options for MySQL and SQLite (#234)

In MySQL it's AUTO_INCREMENT
(see https://dev.mysql.com/doc/refman/8.0/en/create-table.html)
and in SQLite it's AUTOINCREMENT.

We use `ColumnOption::DialectSpecific(Vec<Token>)` to avoid adding a new variant for each vendor-specific column option.

tests/sqlparser_sqlite.rs

@@ -17,6 +17,7 @@
 use sqlparser::ast::*;
 use sqlparser::dialect::GenericDialect;
 use sqlparser::test_utils::*;
+use sqlparser::tokenizer::Token;
 
 #[test]
 fn parse_create_table_without_rowid() {
@@ -55,6 +56,37 @@ fn parse_create_virtual_table() {
     sqlite_and_generic().verified_stmt(sql);
 }
 
+#[test]
+fn parse_create_table_auto_increment() {
+    let sql = "CREATE TABLE foo (bar INT PRIMARY KEY AUTOINCREMENT)";
+    match sqlite_and_generic().verified_stmt(sql) {
+        Statement::CreateTable { name, columns, .. } => {
+            assert_eq!(name.to_string(), "foo");
+            assert_eq!(
+                vec![ColumnDef {
+                    name: "bar".into(),
+                    data_type: DataType::Int,
+                    collation: None,
+                    options: vec![
+                        ColumnOptionDef {
+                            name: None,
+                            option: ColumnOption::Unique { is_primary: true }
+                        },
+                        ColumnOptionDef {
+                            name: None,
+                            option: ColumnOption::DialectSpecific(vec![Token::make_keyword(
+                                "AUTOINCREMENT"
+                            )])
+                        }
+                    ],
+                }],
+                columns
+            );
+        }
+        _ => unreachable!(),
+    }
+}
+
 fn sqlite_and_generic() -> TestedDialects {
     TestedDialects {
         // we don't have a separate SQLite dialect, so test only the generic dialect for now