New files ignored by hot-reload if entire project is inside a hidden folder

### Describe the bug
`dotnet watch` does not trigger a hot-reload when new C# files are added to a project if that project lives inside a hidden directory (a directory whose name starts with '.').

For example, given the following directory structure:
- .hidden
- MyProject
- MyProject.cs
- Program.cs

`dotnet watch` will not accept a newly-added C# file added to MyProject as a reason to hot-reload.

This line of source code is responsible for the issue:
https://github.com/dotnet/sdk/blob/6c36567aec9869fd085fdd855352a722a7a8dd7c/src/Dotnet.Watch/Watch/HotReload/HotReloadDotNetWatcher.cs#L797

### To Reproduce
1. Checkout https://github.com/Ivy-Interactive/DotnetWatchHiddenFolderBug
2. Follow the instructions in README.md

### Further technical details
details of dotnet --info

```
.NET SDK:
Version: 10.0.201
Commit: 4d3023de60
Workload version: 10.0.201
MSBuild version: 18.3.0-release-26153-122+4d3023de6

Runtime Environment:
OS Name: Mac OS X
OS Version: 26.3
OS Platform: Darwin
RID: osx-arm64
Base Path: /usr/local/share/dotnet/sdk/10.0.201/

.NET workloads installed:
There are no installed workloads to display.
Configured to use workload sets when installing new manifests.

Host:
Version: 10.0.5
Architecture: arm64
Commit: a612c2a105

.NET SDKs installed:
6.0.413 [/usr/local/share/dotnet/sdk]
7.0.200 [/usr/local/share/dotnet/sdk]
8.0.406 [/usr/local/share/dotnet/sdk]
9.0.100 [/usr/local/share/dotnet/sdk]
9.0.203 [/usr/local/share/dotnet/sdk]
9.0.306 [/usr/local/share/dotnet/sdk]
10.0.100 [/usr/local/share/dotnet/sdk]
10.0.102 [/usr/local/share/dotnet/sdk]
10.0.201 [/usr/local/share/dotnet/sdk]

.NET runtimes installed:
Microsoft.AspNetCore.App 6.0.21 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 7.0.3 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 8.0.13 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 9.0.0 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 9.0.4 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 9.0.10 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 10.0.0 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 10.0.2 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 10.0.5 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.NETCore.App 6.0.14 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 6.0.21 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 7.0.3 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 8.0.13 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 9.0.0 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 9.0.4 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 9.0.10 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 10.0.0 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 10.0.2 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 10.0.5 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

Other architectures found:
x64 [/usr/local/share/dotnet/x64]
registered at [/etc/dotnet/install_location_x64]

Environment variables:
Not set

global.json file:
Not found

Learn more:
https://aka.ms/dotnet/info

Download .NET:
https://aka.ms/dotnet/download
```