Fix issue 434: Add connector level proxy configurations

[wangshu3000]

This is a PR to fix issue: #434

In this PR, i added 2 parameters to the connector configurations.
splunk.hec.http.proxy.host - The proxy host
splunk.hec.http.proxy.port - The proxy port

This proxy is setup at the connector level, the splunk connector can use it's own proxy.
If these 2 parameters were configured, it'll use this proxy when connecting to HEC endpoint.
Otherwise, it'll use the JVM level proxy setting in JVM_OPTS.

This provides us the capability to use a different proxy for this connector. No matter how the global JVM_OPTS proxy was configured.

[wangshu3000]

Hi @wojtekzyla @VihasMakwana
Could you please hep to review this PR if you have time?
This is a PR to add proxy related configuration settings, so that we can configure connector level proxy.

Thanks.

[wojtekzyla]

Hi @wangshu3000 sure I'll review this

[wangshu3000]

@wojtekzyla Not sure if you got chance to review my change, i have updated the description based on your suggestion. Could you please have a review? Thanks.

[shijiadong2022]

@wojtekzyla I wonder if you could help review this one when you have a chance?

[wojtekzyla]

Could you add some empty commit to restart the workflow?

[wangshu3000]

Thanks @wojtekzyla for your approval, i have retriggered the CI Build Test, could you please approve the flow? Thanks.

[github-actions]

Unit Test Results

175 tests   175 ✅  38s ⏱️
 24 suites    0 💤
 24 files      0 ❌

Results for commit b45a55d.

[wangshu3000]

Thanks @wojtekzyla
Looks like the CI Build was failed at fossa-scan step, looks like some dependencies are not compliant, not sure if i should bump the version in my PR or it can be bypassed?