Support type-safe project dependencies in config

**Is your feature request related to a problem? Please describe.**

Can't use [type-safe project accessors](https://docs.gradle.org/7.0/userguide/declaring_dependencies.html#sec:type-safe-project-accessors) in config:

```kotlin
exclude("my-project:subproject")
```
We migrated to type-safe project accessors but have to use string paths in configs.
It'd great to use the same notation.

**Describe the solution you'd like**

To pass type-safe project accessors to the config:

```kotlin
exclude(projects.myProject.subproject)
```

**Describe alternatives you've considered**

```kotlin
exclude(projects.myProject.subproject.dependencyProject.path)
```

**Additional context**

The issue names no files, tests, or entry points. Start by locating the config API that accepts exclude("my-project:subproject") and inspect how project dependencies are represented; done means exclude(projects.myProject.subproject) is accepted while existing string paths remain supported, with coverage for both forms.

Written by the indexing model from the issue text.