(you don't have to strictly follow this form)

**Describe the bug**
When using `ORDER BY column_name COLLATE 'en'`, `COLLATE` is ignored if `column_name` is the primary key
 
**How to reproduce**
* version 21.1.2
* `CREATE TABLE` statements for all tables involved:
```
CREATE TABLE test.test_collation
(
    `v` String,
    `v2` String
)
ENGINE = MergeTree
ORDER BY v
SETTINGS index_granularity = 8192
```
* Sample data:
```
insert into test.test_collation values ('A', 'A')
insert into test.test_collation values ('B', 'B')
insert into test.test_collation values ('C', 'C')
insert into test.test_collation values ('a', 'a')
insert into test.test_collation values ('b', 'b')
insert into test.test_collation values ('c', 'c')
```
* Queries to run that lead to unexpected result
Primary key
```
SELECT *
FROM test.test_collation
ORDER BY v ASC COLLATE 'en'

Query id: fa84ae7a-abe7-4886-99cd-eba7ad5d5fc4

┌─v─┬─v2─┐
│ A │ A  │
│ B │ B  │
│ C │ C  │
│ a │ a  │
│ b │ b  │
│ c │ c  │
└───┴────┘
```
Separate column
```
SELECT *
FROM test.test_collation
ORDER BY v2 ASC COLLATE 'en'

Query id: 04401f85-3cb2-442c-8c89-e3328d1615cd

┌─v─┬─v2─┐
│ a │ a  │
│ A │ A  │
│ b │ b  │
│ B │ B  │
│ c │ c  │
│ C │ C  │
└───┴────┘
```

**Expected behavior**
Both of these queries to return the rows in the same order

: definition.order_by->children)
        {
            
            const auto & order_by_element
                = column_ast->as<ASTOrderByElement &>();
            
            desc.order_by.push_back(
                SortColumnDescription(
                    order_by_element.children.front()->getColumnName(),
                    order_by_element.direction,
                    order_by_element.nulls_direction));
        }
    }
    desc.full_sort_description = desc.partition_by;
    desc.full_sort_description.insert(desc.full_sort_description.end(),
        desc.order_by.begin(), desc.order_by.end());
    if (definition.frame.type != WindowFrame::FrameType::Rows
        && definition.frame.type != WindowFrame::FrameType::Range)
    {
        std::string name = definition.frame.type == WindowFrame::FrameType::Rows
            ? "ROWS"
            : definition.frame.type == WindowFrame::FrameType::Groups
                ? "GROUPS" : "RANGE";
        throw Exception(ErrorCodes::NOT_IMPLEMENTED,
            "Window frame '{}' is not implemented (while processing '{}')",
            name, ast->formatForErrorMessage());
    }
    desc.frame = definition.frame;
}
void ExpressionAnalyzer::makeWindowDescriptions(ActionsDAGPtr actions)