Consider building a 'bare' directory

### Summary

Given a directory tree like

```
/src
|_ app
|_ app.csproj
|_ tests
|_ tests.csproj
```

It would be nice if running `dotnet build` at the `/src` level would glob and create a build request that built all of the discovered projects. It would be even _nicer_ if there was also an `--exclude-glob` option that could take a glob pattern, be specified multiple times, and would apply to the discovered project list.

This would reduce the need to have solutions/traversal projects to 'connect the dots', and it would also align with DevKit-level initiatives to make user actions "do the right thing" at various levels of the file system right-click menus.

### Background and Motivation

The main request here is to solve a UX friction point when there is a reasonable default behavior. When a build is triggered

* if there is not a buildable thing presented
* and there is not a solution-like thing in the current directory
* and there is not a project-like thing in the current directory
* then glob the current directory and discover the things to build

Having this feature means that there is much less pressure to have slnf or traversal projects that exist only as 'stubs'.

### Proposed Feature

When a build is triggered via the command line:

* if there is not a buildable thing presented
* and there is not a solution-like thing in the current directory
* and there is not a project-like thing in the current directory
* then glob the current directory and discover the things to build

### Alternative Designs

_No response_