[C][Client] Support progress function of libcurl

[ityuhui]

Hi @wing328 @zhemant @michelealbano

This is a feature enhancement.
libcurl has a mechanism of progress callback function.
https://curl.se/libcurl/c/CURLOPT_XFERINFOFUNCTION.html
That can be used to do some operation ( e.g. display download/upload progress information ) when the transfer is in progress.
This PR introduces this feature into c client.

It also can be used to stop an endless http(s) request. The detail can be found at kubernetes-client/c#39

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[wing328]

Please merge the latest master into this branch, which should fix the CI failures.

[ityuhui]

Please merge the latest master into this branch, which should fix the CI failures.

Sure. I will do it.

[ityuhui]

Hi @wing328

I have merged (git rebase upstream/master) the master code on yesterday evening. But ci/circleci: build still failed.
Are you sure the latest code has fixed the CI failure ?

[wing328]

Looks like https://repo.maven.apache.org:443 was throttling our connections as the project is too active.

Nov 23, 2020 1:42:39 PM org.apache.maven.wagon.providers.http.httpclient.impl.execchain.RetryExec execute
INFO: I/O exception (java.net.SocketException) caught when processing request to {s}->https://repo.maven.apache.org:443: Connection reset
Nov 23, 2020 1:42:39 PM org.apache.maven.wagon.providers.http.httpclient.impl.execchain.RetryExec execute
INFO: Retrying request to {s}->https://repo.maven.apache.org:443
Nov 23, 2020 1:42:39 PM org.apache.maven.wagon.providers.http.httpclient.impl.execchain.RetryExec execute
INFO: I/O exception (java.net.SocketException) caught when processing request to {s}->https://repo.maven.apache.org:443: Connection reset
Nov 23, 2020 1:42:39 PM org.apache.maven.wagon.providers.http.httpclient.impl.execchain.RetryExec execute
INFO: Retrying request to {s}->https://repo.maven.apache.org:443
Nov 23, 2020 1:42:39 PM org.apache.maven.wagon.providers.http.httpclient.impl.execchain.RetryExec execute
INFO: I/O exception (java.net.SocketException) caught when processing request to {s}->https://repo.maven.apache.org:443: Connection reset
Nov 23, 2020 1:42:39 PM org.apache.maven.wagon.providers.http.httpclient.impl.execchain.RetryExec execute
INFO: Retrying request to {s}->https://repo.maven.apache.org:443

Just restarted the circleci job. Let's see how that goes.

[wing328]

CircleCI tests passed via https://app.circleci.com/pipelines/github/OpenAPITools/openapi-generator/7126/workflows/6196c76a-817f-4cd4-9f4f-2ed359b52266/jobs/20610

[ityuhui]

Thank you @wing328