Adds red text that appears when the VPN fails to start or stop. After an
error, any manual start/stop operation will clear the error.

Contributes to #40

- Enables assembly version verification
- Enables authenticode verification
- Adds local machine registry config options to enable/disable either of
these

Closes #41 
Closes #45

Contains a gRPC client for mutagen's synchronization API.

All required .proto files are vendored using a new script
`Update-Proto.ps1`, which finds all required files by scanning `import`
directives.

The vendored files are modified to add `csharp_namespace` and a MIT
license header from mutagen.

Example usage:
```cs
using var client = new MutagenClient(@"C:\Users\dean\.mutagen");
var res = await client.Synchronization.ListAsync(new ListRequest
{
    Selection = new Selection
    {
        All = true,
    },
});

foreach (var state in res.SessionStates)
    Console.WriteLine(state);
```

Closes coder/internal#378

`Publish.ps1` now downloads (if unmodified) the necessary mutagen files
from our GCS bucket. These files aren't checked into the repo since they
are large, but they will be cached and ignored in the workdir.

`mutagen.exe` and `mutagen-agents.tar.gz` will appear in the same
directory as `wintun.dll` in the install.

```powershell
PS C:\Users\dean\git\coder-desktop-windows> ls .\publish\buildtemp-1.2.3.4-x64\vpn


    Directory: C:\Users\dean\git\coder-desktop-windows\publish\buildtemp-1.2.3.4-x64\vpn


Mode                 LastWriteTime         Length Name
----                 -------------         ------ ----
-a----         1/03/2025     12:02           5431 LICENSE.WINTUN.txt
-a----        10/03/2025     11:58       17964207 mutagen-agents.tar.gz
-a----        10/03/2025     11:58       13797376 mutagen.exe
-a----         1/03/2025     15:20         427552 wintun.dll
```

Updating to a new mutagen version is as simple as updating
`$mutagenVersion` in `Publish.ps1`.

Closes #25

Updates CredentialModel to have an additional state `Unknown` during
startup while credentials are validated in the background asynchronously
(15s timeout).

While loading credentials on startup, the tray app shows a loading
message.

While updating credentials, we now check that the server version falls
in our expected range.

The sign in page now uses a WinUI 3 Dialog to show errors.

Closes #42

- Adds support for an array of protobuf "entry points" in
`Mutagen/Update-Proto.ps1`
- Also refactors file modification/writing to be more efficient and to
not include an unnecessary byte order mark and two trailing new lines
- Adds Daemon service to `MutagenClient`

Part of coder/internal#458

fixes coder/internal#380

Adds MutagenController service, which manages the lifecycle of the `mutagen` daemon and exposes methods to query and modify sync sessions.

Sync sessions themselves are a placeholder which will need to be filled out and plumbed thru to the actual API. This just handles daemon lifecycle for now.

Adds `TelemetryEnricher` class and interface to enrich the `StartRequest` message with OS, device ID, and version information.

Also adds the version to `Publish.ps1` so that it is available in released binaries.

Closes #61

- Adds `PauseSyncSession` and `ResumeSyncSession`
- Adds `SyncSessionViewModel` that wraps `SyncSessionModel` and adds
view methods (as you cannot access the parent context if you're in a
`ItemsRepeater` apparently)
- Wires up Initialize, List, Pause, Resume, Terminate and Create in the
file sync UI

## TODO:
- Prevent the app from loading until mutagen finishes initializing
(either successfully or not) (in a different PR)
- Add reinitialization logic to mutagen controller (in a different PR)

Closes #26 
Closes #28 
Closes #29