Testing features not possible on Windows

I am trying to build a feature, and I failed. So I wrote a test to see what failed. However, when trying to execute my test, I get this error:

```
🚀 Launched container.
> containerId: 765681ff36037ff597185005ba19c57bd1db92eccda9bbd6127d536fd97c6c2e

🏃 Starting test(s)...

🧪 Starting 'oh-my-posh' tests...
Error: Exectuable 'chmod' not found on PATH 'C:\Program Files\PowerShell\7;C:\Program Files\Microsoft SDKs\Azure\CLI2\wbin;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Windows\System32\OpenSSH\;C:\Program Files (x86)\NVIDIA Corporation\PhysX\Common;...'.
at EF (C:\Users\SebastianGingter\AppData\Roaming\npm\node_modules\@devcontainers\cli\dist\spec-node\devContainersSpecCLI.js:150:4280)
at async Object.exec (C:\Users\SebastianGingter\AppData\Roaming\npm\node_modules\@devcontainers\cli\dist\spec-node\devContainersSpecCLI.js:150:1655)
at async W0 (C:\Users\SebastianGingter\AppData\Roaming\npm\node_modules\@devcontainers\cli\dist\spec-node\devContainersSpecCLI.js:591:83)
at async WtA (C:\Users\SebastianGingter\AppData\Roaming\npm\node_modules\@devcontainers\cli\dist\spec-node\devContainersSpecCLI.js:572:678)
at async jtA (C:\Users\SebastianGingter\AppData\Roaming\npm\node_modules\@devcontainers\cli\dist\spec-node\devContainersSpecCLI.js:572:197)
at async $H (C:\Users\SebastianGingter\AppData\Roaming\npm\node_modules\@devcontainers\cli\dist\spec-node\devContainersSpecCLI.js:567:190)
at async AiA (C:\Users\SebastianGingter\AppData\Roaming\npm\node_modules\@devcontainers\cli\dist\spec-node\devContainersSpecCLI.js:591:4218)
at async C:\Users\SebastianGingter\AppData\Roaming\npm\node_modules\@devcontainers\cli\dist\spec-node\devContainersSpecCLI.js:591:3506 {
code: 'ENOENT'
}
```

It seems, the `execTest` method in `testCommandImpl.ts` hardcodes a call to `chmod`, which is executed on the `cliHost`. In my case this is Windows, which does not have a `chmod`.

See https://github.com/devcontainers/cli/blob/2a6ab1ac82f4917654205e2a9b1ac928260d902e/src/spec-node/featuresCLI/testCommandImpl.ts#L596

There's another `cliHost.exec()` call to `chmod` in line 539:
https://github.com/devcontainers/cli/blob/2a6ab1ac82f4917654205e2a9b1ac928260d902e/src/spec-node/featuresCLI/testCommandImpl.ts#L539

Maybe the `chmod` should be done in the container, and not on the host?

Start in src/spec-node/featuresCLI/testCommandImpl.ts at the chmod calls around lines 539 and 596, then inspect how execTest invokes cliHost.exec(). Reproduce the feature test flow on Windows and verify that tests no longer fail because chmod is unavailable on the host; add or update coverage if the file provides relevant tests.

Written by the indexing model from the issue text.