Replace hardcoded percentages with values from a file

[hmeriann]

This PR will replace hardcoded percentages from the fuzzer with values defined in a file, as it mentioned in the #23

[Tmonster]

Looks good! I don't think the RandomsConfig needs to be a friend class, instead you can make the RandomConfig a member of the StatementGenerator. Ie...

class StatementGenerator {
public:
    RandomsConfig percentage_selector;
}

[Tmonster]

Maybe the RandomNumsConfig could be an unorderdered_map<percentages_enum, idx_t> ?

You will have to create an Enum (see duckdb/common/enums/logical_operator_type.hpp for an example).

In the future it will make it easier to manage the percentages, add new ones etc.

[Tmonster]

Looks much better.

looks like you don't use the file handle though.
Now you can start adding more percentages as well if you want. Feel free to create a GitHub actions file that runs the fuzzer with a config file and one without

[Tmonster]

Looks good. Just the one comment.

also, I can imagine you may end up adding many ENUMS for each case. You can also just create enums like RandomPercentagesEnum::DEFAULT_XX_PERCENT so that your enum library doesn't get insanely big. Eventually the enums in the statement generation code can get their own enums as we continue to work on and expand this functionality

[Tmonster]

Can the RandomNumsConfig be a class? That should make things easier to maintain in my opinion