Cannot use NULL in array_* functions

[jackbentley]

Similar to #240, some array functions such as ARRAY_REMOVE allow the value NULL to be passed as the second parameter:

SELECT array_remove(fb.foo, NULL) AS bar FROM FooBar fb

However, due to the usage of ArithmeticPrimary you would get this error is you tried to pass NULL:

[Syntax Error] line 0, col 51: Error: Expected Literal, got 'NULL'

You can currently work around this by setting a parameter :null as NULL for example.

I'm not sure what node mapping should be used here but I think it may be NewValue? Or possibly might need a custom one.

[martin-georgiev]

Good comment - in the time being, can you please document your workaround as a PR for file https://github.com/martin-georgiev/postgresql-for-doctrine/blob/main/docs/USE-CASES-AND-EXAMPLES.md?
I think it may be useful for other developers.

[martin-georgiev]

Addressed with #322