Remove wrapping with extra msgpack array in stored procedure return values

Since https://github.com/tarantool/tarantool/issues/4799 is fixed, now we can use the compat.c_func_iproto_multireturn = 'new' option (introduced in this commit) which will make our rust stored procedure not add an extra msgpack array to the return values.

Current behaviour

This will make our "proc api" more friendly, e.g. .proc_version_info now can only return something like this:

[{"picodata_version": "23.12.1", "proc_api_version": "0.1.0"}]

or this

["23.12.1", "0.1.0"]

New behaviour

But after the fix we'll be able to return this:

{"picodata_version": "23.12.1", "proc_api_version": "0.1.0"}

Breaking compatibility

However this will be a breaking change and will require to fix code in many different places including sbroad.

changed the description

mentioned in issue #467 (closed)

mentioned in commit 38350456

mentioned in merge request !840 (merged)

mentioned in commit 0ad93b18

mentioned in commit b688a775

mentioned in commit fb5272d0

mentioned in commit 22738e64

mentioned in commit d0b7f8f9

closed with merge request !840 (merged)

closed with commit d0b7f8f9