Add server-side limit flag for bytes

[manedurphy]

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• Version of iperf3 (or development branch, such as master or
  3.1-STABLE) to which this pull request applies: master

• Issues fixed (if any): N/A

• Brief description of code changes (suitable for use as a commit message):

  • Similar to Add Time Flag For The Iperf Server Process #1684, this change allows the server process to limit how many bytes that the client may send or receive for the test behind the --server-max-bytes flag

Accepted Test

# Server
./src/iperf3 --server --server-max-bytes 50M
-----------------------------------------------------------
Server listening on 5201 (test #1)
-----------------------------------------------------------
Accepted connection from 127.0.0.1, port 43444
[  5] local 127.0.0.1 port 5201 connected to 127.0.0.1 port 43458
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-1.00   sec  50.0 MBytes   419 Mbits/sec                  
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-1.00   sec  50.0 MBytes   419 Mbits/sec                  receiver
-----------------------------------------------------------
Server listening on 5201 (test #2)
-----------------------------------------------------------

# Client
./src/iperf3 --client 127.0.0.1 --bytes 50M
Connecting to host 127.0.0.1, port 5201
[  5] local 127.0.0.1 port 43458 connected to 127.0.0.1 port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-1.00   sec  50.0 MBytes   419 Mbits/sec    0    639 KBytes       
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-1.00   sec  50.0 MBytes   419 Mbits/sec    0            sender
[  5]   0.00-1.00   sec  50.0 MBytes   419 Mbits/sec                  receiver

iperf Done.

Rejected Test

# Server
./src/iperf3 --server --server-max-bytes 50M
-----------------------------------------------------------
Server listening on 5201 (test #1)
-----------------------------------------------------------
iperf3: error - client's requested bytes exceeds the server's maximum permitted limit
-----------------------------------------------------------
Server listening on 5201 (test #2)
-----------------------------------------------------------

# Client
./src/iperf3 --client 127.0.0.1 --bytes 52M
Connecting to host 127.0.0.1, port 5201
iperf3: error - client's requested bytes exceeds the server's maximum permitted limit

[bmah888]

Thanks for the PR! We'll take a look at it.