VIEW: COUNT and other aggregate functions do not work inside a view

[jepett0]

To reproduce:

0. Create the necessary table to read from:

CREATE TABLE user_group_members (
    group_id uint32,
    user_id uint32,
    PRIMARY KEY (group_id, user_id)
);

1. Create a view:

CREATE VIEW user_group_view WITH (security_invoker = TRUE) AS
    SELECT COUNT(user_id) AS members_count
    FROM `/Root/user_group_members`; -- write your own path to the `user_group_members` table

2. Select from the view:

SELECT * FROM user_group_view;

3. Observe an error:

Status: GENERIC_ERROR
Issues: 
<main>: Error: Type annotation, code: 1030
    <main>:1:1: Error: At function: RemovePrefixMembers, At function: RemoveSystemMembers, At function: PersistableRepr, At function: SqlProject, At function: PersistableRepr, At function: SqlProject
        <main>:1:48: Error: At function: AssumeColumnOrderPartial
            <main>:1:8: Error: At function: Aggregate, At function: Apply
                <main>:1:8: Error: Expected callable type, but got: Unit

[jepett0]

PRs in stable:
#7501
#7523