Make ExtensionBaseUrl configurable.

[chunhualiu]

I am using a github mirror. So I want to make extensionBaseUrl configurable.

[thedemons]

Hello, thanks for the PR!

Are there any reasons that you need to use a GitHub mirror for downloading? I feel like this setting is a bit problematic and would confuse the users because the URL needs to be in a specific format. We also need to (prompt the user to) re-download the language server after applying the setting, or at least warn the user in the description that they would need to manually delete the current one to force a re-download.

[chunhualiu]

Hello, thanks for the PR!

Are there any reasons that you need to use a GitHub mirror for downloading? I feel like this setting is a bit problematic and would confuse the users because the URL needs to be in a specific format. We also need to (prompt the user to) re-download the language server after applying the setting, or at least warn the user in the description that they would need to manually delete the current one to force a re-download.

Because in China, github is not always accessible.
I am using an open source github proxy which acts like a mirror: https://github.com/hunshcn/gh-proxy
It can provide github mirror URL in format like https://gh.api.99988866.xyz/https://github.com/Exafunction/CodeiumVisualStudio/...
That's why I keep the original URL in CodeiumVS/SettingsPage.cs, so user can easily configure the URL.
Since github is not accessible, so the first download will fail.
After user correct the URL, I do found Codeium plugin prompts a re-download.
If no re-download, simply restart VS will cause download from new URL too.
Also if there is a current one, it is no need to manually delete the current one, because it's a mirror, do a re-download will get the same thing.

[chunhualiu]

BTW. I also made below changes:

-        await _package.LogAsync($"Downloading language server v{_languageServerVersion}");
+        await _package.LogAsync($"Downloading language server v{_languageServerVersion} from {_languageServerURL}");

So user can know it's downloading from new URL or not.

[thedemons]

Merged. Thank you!