Avi Kivity 936de92876 Merge 'cql3: Add evaluate(expression) and use instead of term::bind()' from Jan Ciołek ...

This PR adds the function:
```c++
constant evaluate(const expression&, const query_options&);
```
which evaluates the given expression to a constant value.
It binds all the bound values, calls functions, and reduces the whole expression to just raw bytes and `data_type`, just like `bind()` and `get()` did for `term`.

The code is often similar to the original `bind()` implementation in `lists.cc`, `sets.cc`, etc.

* For some reason in the original code, when a collection contains `unset_value`, then the whole collection is evaluated to `unset_value`. I'm not sure why this is the case, considering it's impossible to have `unset_value` inside a collection, because we forbid bind markers inside collections. For example here: cc8fc73761/cql3/lists.cc (L134)
This seems to have been introduced by Pekka Enberg in 50ec81ee67, but he has left the company.
I didn't change the behaviour, maybe there is a reason behind it, although maybe it would be better to just throw `invalid_request_exception`.
* There was a strange limitation on map key size, it seems incorrect: cc8fc73761/cql3/maps.cc (L150), but I left it in.
* When evaluating a `user_type` value, the old code tolerated `unset_value` in a field, but it was later converted to NULL. This means that `unset_value` doesn't work inside a `user_type`, I didn't change it, will do in another PR.
* We can't fully get rid of `bind()` yet, because it's used in `prepare_term` to return a `terminal`. It will be removed in the next PR, where we finally get rid of `term`.

Closes #9353

* github.com:scylladb/scylla:
  cql3: types: Optimize abstract_type::contains_collection
  cql3: expr: Convert evaluate_IN_list to use evaluate(expression)
  cql3: expr: Use only evaluate(expression) to evaluate term
  cql3: expr: Implement evaluate(expr::function_call)
  cql3: expr: Implement evaluate(expr::usertype_constructor)
  cql3: expr: Implement evaluate(expr::collection_constructor)
  cql3: expr: Implement evaluate(expr::tuple_constructor)
  cql3: expr: Implement evaluate(expr::bind_variable)
  cql3: Add contains_collection/set_or_map to abstract_type
  cql3: expr: Add evaluate(expression, query_options)
  cql3: Implement term::to_expression for function_call
  cql3: Implement term::to_expression for user_type
  cql3: Implement term::to_expression for collections
  cql3: Implement term::to_expression for tuples
  cql3: Implement term::to_expression for marker classes
  cql3: expr: Add data_type to *_constructor structs
  cql3: Add term::to_expression method
  cql3: Reorganize term and expression includes

2021-09-26 12:58:11 +03:00

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