Feature Request: Support HttpHeaders in Server Configuration

[acidbee]

Our organization has moved our artifact repository to a system that uses custom headers authentication. These headers are currently not picked up and sent to the transport layer/Wagon. Our CI system is failing on Gradle builds because I cannot properly authenticate artifact repository to get dependencies.

Developer's settings.xml look like this, utilizing a private token:

   <server>
      <id>gitlab-maven</id>
      <configuration>
        <httpHeaders>
          <property>
            <name>Private-Token</name>
            <value>Secret</value>
          </property>
        </httpHeaders>
      </configuration>
    </server>

Our CI settings.xml looks like this, allowing to token to rotate per job:

      <server>
          <id>gitlab-maven</id>
          <configuration>
              <httpHeaders>
                  <property>
                      <name>Job-Token</name>
                      <value>${env.CI_JOB_TOKEN}</value>
                  </property>
              </httpHeaders>
          </configuration>
      </server>

A workaround we've been trying in the build.gradle file has the potential but occasionally doesn't play nice with our IDEs

maven {
        name = "gitlab-maven"
        url = uri("https://gitlab.com/api/v4/projects/14262838/packages/maven")
        val credentialProperties = listOf(
          EnvProperty("CI_JOB_TOKEN", "Job-Token"),
          EnvProperty("GITLAB_PRIVATE_TOKEN", "Private-Token")
        )
        val credential = credentialProperties.mapNotNull(EnvProperty::asCredential).firstOrNull() ?: throw RuntimeException("Gitlab credentials not found")

        credentials(HttpHeaderCredentials::class) {
          name = credential.name
          value = credential.value
        }

        authentication {
          create<HttpHeaderAuthentication>("header")
        }
    }

I will attempt to work on a pull request for this.