Co-authored-by: Vladislav <Shpilevoy&lt;v.shpilevoy@tarantool.org>

Part of #4398

@TarantoolBot document
Title: Custom error types for Lua errors

Errors can be created in 2 ways: `box.error.new()` and `box.error()`.

Both used to take either `code, reason, <reason string args>` or
`{code = code, reason = reason, ...}` arguments.

Now in the first option instead of code a user can specify a
string as its own error type. In the second option a user can
specify both code and type. For example:

```Lua
box.error('MyErrorType', 'Message')
box.error({type = 'MyErrorType', code = 1024, reason = 'Message'})
```
Or no-throw version:
```Lua
box.error.new('MyErrorType', 'Message')
box.error.new({type = 'MyErrorType', code = 1024, reason = 'Message'})
```
When a custom type is specified, it is shown in `err.type`
attribute. When it is not specified, `err.type` shows one of
built-in errors such as 'ClientError', 'OurOfMemory', etc.

Name length limit on the custom type is 63 bytes. All what is
longer is truncated.

Original error type can be checked using `err.base_type` member,
although normally it should not be used. For user-defined types
base type is 'CustomError'.

For example:
```
tarantool> e = box.error.new({type = 'MyErrorType', code = 1024, reason = 'Message'})
---
...

tarantool> e:unpack()
---
- code: 1024
  trace:
  - file: '[string "e = box.error.new({type = ''MyErrorType'', code..."]'
    line: 1
  type: MyErrorType
  custom_type: MyErrorType
  message: Message
  base_type: CustomError
...
```