No GitHub repositories found when using SSH aliases

**Describe the bug**
When using SSH config aliases (see the example below), the GitHub Actions extension returns the error message "No GitHub repositories found". SSH aliases are often used when a user has multiple GitHub accounts that have separate SSH keys.

This only occurs when using an alias that does not include `github.com` in the alias name. If I were to change the alias name to, for example, `personal.github.com`, as well as the remote, then the extension works without issue.

**To Reproduce**
Steps to reproduce the behavior:
1. Create an alias in your SSH config file (e.g., ~/.ssh/config) with any name that does not include `github.com`.
2. Switch your origin remote to use the alias (e.g., git@alias:username/repo.git)
3. Reload VSCode
4. Switch to the GitHub Actions extension and see "No GitHub repositories found"
5. Switch your origin remote back to a standard "github.com" alias
6. Reload VSCode
7. Switch to the GitHub Actions extension and see standard functionality.

**Expected behavior**
GitHub Actions would work regardless of the SSH config alias.

**Extension Version**
`v0.27.2`

**Additional context**
Logs from the extension when using a non-github.com alias:

```
Activating GitHub Actions extension...
Error getting GitHub context
Invalid URL
TypeError: Invalid URL
at new URL (node:internal/url:818:25)
at /Users/josephgruber/.vscode/extensions/github.vscode-github-actions-0.27.2/dist/extension-node.js:1:1158030
at async Promise.all (index 0)
at async /Users/josephgruber/.vscode/extensions/github.vscode-github-actions-0.27.2/dist/extension-node.js:1:1157669
at async De (/Users/josephgruber/.vscode/extensions/github.vscode-github-actions-0.27.2/dist/extension-node.js:1:1157518)
at async os (/Users/josephgruber/.vscode/extensions/github.vscode-github-actions-0.27.2/dist/extension-node.js:1:1339675)
at async Lb.n (file:///Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/api/node/extensionHostProcess.js:112:13382)
at async Lb.m (file:///Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/api/node/extensionHostProcess.js:112:13345)
at async Lb.l (file:///Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/api/node/extensionHostProcess.js:112:12801)
```

首先跟踪扩展激活过程以及 GitHub 上下文查找；当 remote 使用非 github.com 的 SSH 别名时，该查找会因 Invalid URL 而失败。使用 issue 中描述的 SSH 配置和 remote 形式复现问题，然后验证仓库发现功能对带别名的 GitHub remote 和标准 GitHub remote 都能正常工作。

由索引模型根据 Issue 内容生成。