Fix parsing `ALTER TABLE ... ADD COLUMNS (...)`

[njaremko]

The current behaviour fails when it encounters ADD COLUMNS and merges everything in the () into one string with no whitespace.

So ALTER TABLE catalog.table.name ADD COLUMNS (apples int) becomes ALTER TABLE catalog.table.name ADD COLUMNS (applesint).

This commit adds an understanding of ALTER TABLE ... ADD COLUMNS to the grammar.

[manticore-projects]

Thank you for your contribution, please fix formatting exception by running './gradlew :spotlessApply' to fix these violations.

[njaremko]

Done

[manticore-projects]

Thank you for your contribution!