Implement asynchronous http transfer

[intuibase]

Requirements:

• integrates with OTel SDK
• possibility to disable and use the default OTel SDK transfer
• troubleshooting logs
• unit tests
• test with Apache, FPM and CLI
• add config flags to docs

[intuibase]

Test without async transport

ab -n 100 -c 5 http://localhost:8080/pdo/sqlite.php
This is ApacheBench, Version 2.3 <$Revision: 1879490 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking localhost (be patient).....done


Server Software:        Apache/2.4.56
Server Hostname:        localhost
Server Port:            8080

Document Path:          /pdo/sqlite.php
Document Length:        64055 bytes

Concurrency Level:      5
Time taken for tests:   5.444 seconds
Complete requests:      100
Failed requests:        99
   (Connect: 0, Receive: 0, Length: 99, Exceptions: 0)
Total transferred:      7524377 bytes
HTML transferred:       7504777 bytes
Requests per second:    18.37 [#/sec] (mean)
==============================================
Time per request:       272.222 [ms] (mean)
Time per request:       54.444 [ms] (mean, across all concurrent requests)
==============================================
Transfer rate:          1349.64 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.0      0       0
Processing:   183  254 175.1    202    1313
Waiting:       18   27  12.3     23     107
Total:        184  254 175.1    202    1313

Percentage of the requests served within a certain time (ms)
  50%    202
  66%    212
  75%    216
  80%    228
  90%    346
  95%    527
  98%   1312
  99%   1313
 100%   1313 (longest request)

Test with async transport:

ab -n 100 -c 5 http://localhost:8080/pdo/sqlite.php
This is ApacheBench, Version 2.3 <$Revision: 1879490 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking localhost (be patient).....done


Server Software:        Apache/2.4.56
Server Hostname:        localhost
Server Port:            8080

Document Path:          /pdo/sqlite.php
Document Length:        92249 bytes

Concurrency Level:      5
Time taken for tests:   2.610 seconds
Complete requests:      100
Failed requests:        99
   (Connect: 0, Receive: 0, Length: 99, Exceptions: 0)
Total transferred:      10350109 bytes
HTML transferred:       10330509 bytes
Requests per second:    38.31 [#/sec] (mean)
==============================================
Time per request:       130.512 [ms] (mean)
Time per request:       26.102 [ms] (mean, across all concurrent requests)
==============================================
Transfer rate:          3872.26 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.1      0       0
Processing:    29  126 247.7     50    1442
Waiting:       20   87 194.1     40    1280
Total:         29  126 247.7     51    1442

Percentage of the requests served within a certain time (ms)
  50%     51
  66%     64
  75%     81
  80%     85
  90%    177
  95%    661
  98%   1324
  99%   1442
 100%   1442 (longest request)