client (--client) should send results to server (--server)

# Context
* Version of iperf3: 3.12
* Hardware: KVM
* Operating system (and distribution, if any): CentOS
* Other relevant information (for example, non-default compilers,
libraries, cross-compiling, etc.): ./configure --disable-static --disable-shared && make

# Bug Report
* Expected Behavior: Server JSON output should have the full result.
* Actual Behavior: Server JSON has zeros for `bytes`, `bits_per_second` (and `jitter_ms`, `lost_packets`, `packets` and `lost_percent` for a downstream UDP test). The server would need to get these results from the client as the server wouldn't know these values. This occurs for server's `sum_sent` for an upstream test and `sum_received` for a downstream test (--reverse).
* Steps to Reproduce
* Server: iperf3 --server --json
* Client: iperf3 --client XXX --reverse [--udp]
* Possible Solution: I believe this should be fairly easy as the client is already sending the relevant details to the server. This can be seen with the client and/or server in debug mode (--debug). I can't seem to find the code that includes the server's result data in the client.

Example Server Output for upstream test from client:
```
get_results
{
"cpu_util_total": 6.6487283974503457,
"cpu_util_user": 0.73126039279357624,
"cpu_util_system": 6.248840627985695,
"sender_has_retransmits": 0,
"streams": [{
"id": 1,
"bytes": 3751936,
"retransmits": 1.8446744073709552e+19,
"jitter": 0,
"errors": 0,
"packets": 229,
"start_time": 0,
"end_time": 3.000103
}, {
"id": 3,
"bytes": 3751936,
"retransmits": 1.8446744073709552e+19,
"jitter": 0,
"errors": 0,
"packets": 229,
"start_time": 0,
"end_time": 3.000104
}]
}
...
"sum_sent": {
"start": 0,
"end": 3.00269,
"seconds": 3.00269,
"bytes": 0,
"bits_per_second": 0,
"jitter_ms": 0,
"lost_packets": 0,
"packets": 0,
"lost_percent": 0,
"sender": true
},
"sum_received": {
"start": 0,
"end": 3.00269,
"seconds": 3.00269,
"bytes": 7503872,
"bits_per_second": 19992398.815728564,
"jitter_ms": 0.0138530240674317,
"lost_packets": 0,
"packets": 458,
"lost_percent": 0,
"sender": false
}
```

Example Server Output for downstream (--reverse) test from client:
```
get_results
{
"cpu_util_total": 0,
"cpu_util_user": 0.099650194600221675,
"cpu_util_system": 0.3321008818710055,
"sender_has_retransmits": 1.8446744073709552e+19,
"streams": [{
"id": 1,
"bytes": 3751936,
"retransmits": 1.8446744073709552e+19,
"jitter": 1.859010951280376e-05,
"errors": 0,
"packets": 229,
"start_time": 0,
"end_time": 3.000152
}, {
"id": 3,
"bytes": 3751936,
"retransmits": 1.8446744073709552e+19,
"jitter": 5.4381090362488954e-06,
"errors": 0,
"packets": 229,
"start_time": 0,
"end_time": 3.000153
}]
}
...
"sum_sent": {
"start": 0,
"end": 3.000182,
"seconds": 3.000182,
"bytes": 7503872,
"bits_per_second": 20009111.447238866,
"jitter_ms": 0,
"lost_packets": 0,
"packets": 458,
"lost_percent": 0,
"sender": true
},
"sum_received": {
"start": 0,
"end": 3.000182,
"seconds": 3.000182,
"bytes": 0,
"bits_per_second": 0,
"jitter_ms": 0,
"lost_packets": 0,
"packets": 0,
"lost_percent": 0,
"sender": false
}
```