Abstraction for expected error messages

[mrigger]

To specify the expected error messages for a SQL statement, we currently use Collection<String>, see https://github.com/sqlancer/sqlancer/blob/af4374fb62419aed966c074b7888ddc78a98313e/src/sqlancer/Query.java#L27

It would be desirable to introduce an abstraction to also allow, for example, specifying regular expressions to cover multiple expected error messages at once, and thus make expected error messages more descriptive (since without using regular expressions, we need to check for the shortest common string).

[mrigger]

In https://github.com/sqlancer/sqlancer/blob/a195cdd0b4a97cf1113c4bded2e1a41281d4a26a/src/sqlancer/common/query/ExpectedErrors.java, we could do the following:

• Add a field with a list of regular expressions.
• Add methods addRegex and addAllRegexes.
• Check whether any regexes match in errorIsExpected.
• Add test cases to https://github.com/sqlancer/sqlancer/blob/a195cdd0b4a97cf1113c4bded2e1a41281d4a26a/test/sqlancer/TestExpectedErrors.java.
• Start refactoring by using the newly-added functionality at some places (as a proof of concept). For example, the CockroachDB implementation might be a good place: https://github.com/sqlancer/sqlancer/blob/a195cdd0b4a97cf1113c4bded2e1a41281d4a26a/src/sqlancer/cockroachdb/CockroachDBErrors.java#L214.

[mrigger]

@albertZhangTJ, do you want to have a look at this issue? I think working on this would be relevant, as we also need to think about how we could generate or specify the list of ExpectedErrors in your DSL.