支持多次调用AdddApollo()以添加namespace.

[czd890]

支持多次调用AdddApollo()以添加namespace.

参考用法:

LibA
  AddLibANamespaces(this IConfigurationBuilder builder){
    builder.AddApollo().AddNamespace("LibA",ConfigFileFormat.Json)
}

LibB
  AddLibBNamespaces(this IConfigurationBuilder builder){
    builder.AddApollo().AddNamespace("LibB")
}

Main
IConfigurationBuilder builder;
builder
  .AddApollo(apolloOptions)
  .AddJsonFile(..)
  .AddLibANamespaces()
  .AddLibBNamespaces()
  .AddApollo()
  .AddNamespace("Main",ConfigFileFormat.Yml)
  .AddCommandLine(...)

[github-actions[bot]]

CLA Assistant Lite bot:
Thank you for your submission, we really appreciate it. Like many open-source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution. You can sign the CLA by just posting a Pull Request Comment same as the below format.

---

I have read the CLA Document and I hereby sign the CLA

---

Calvin seems not to be a GitHub user. You need a GitHub account to be able to sign the CLA. If you have already a GitHub account, please add the email address used for this commit to your account.
_{You can retrigger this bot by commenting recheck in this Pull Request}

[czd890]

I have read the CLA Document and I hereby sign the CLA