Nested comments were broken by the sqlparser v0.54 release

[lovasoa]

Nested /* comments used to be parsed as such by sqlparser, but have been broken by the 0.54 release.

The following works in postgresql and mssql:

select /* /* comment */ */ 1;

and it used to be parsed correctly by sqlparser, but now is not.

Initially reported in sqlpage/SQLPage#834

[lovasoa]

Nested comments are explicitly supported in Microsoft SQL Server: https://learn.microsoft.com/en-us/sql/t-sql/language-elements/slash-star-comment-transact-sql