Add format_object field to spaces

Related dev. issue(s): https://github.com/tarantool/tarantool/commit/cf1c250eb1af25d29cd93509af653479428c5fed

Product: Tarantool
Since: 3.5
Root document: https://www.tarantool.io/en/doc/latest/reference/reference_lua/box_space/
SME: @ locker

Details

Since: 3.5

The format_object field returns the box.tuple.format object associated
with the space’s format. It provides the same API as box.tuple.format,
including :validate() and other.

Example:

space = box.schema.space.create('test', {
    format = {
        {name = 'id', type = 'unsigned'},
        {name = 'name', type = 'string'}
    }
})

space.format_object:validate({123, 'example'})

TW Guidelines

It is suggested that a new page on the same level with https://www.tarantool.io/en/doc/latest/reference/reference_lua/box_space/format/ is to be created.

Hint: the existing method space_object:format() returns a table, the new format_object field returns an object

Do together with #5134

Start with the existing box_space/format/ page and the box.tuple.format API described in the issue. Create a new page at the same documentation level explaining space.format_object, its object API including :validate(), and the distinction from space:format(); include the provided example as the completion check.