IProjectProperties contains no API for getting a property value with dimensional conditions

## Summary
The [IProjectProperties interface](http://index/?rightProject=Microsoft.VisualStudio.ProjectSystem&file=ProjectProperties%5CIProjectProperties.cs&line=89) contains a function which allows you to set a property value for some dimensional conditions:
`Task SetPropertyValueAsync(string propertyName, string unevaluatedPropertyValue, IReadOnlyDictionary? dimensionalConditions = null);`

However, there is no symmetric function that allows us to get a property value under specific dimensional conditions.

I was expecting something like this to exist and was surprised to learn it doesn't:
`Task GetEvaluatedPropertyValueAsync(string propertyName, IReadOnlyDictionary? dimensionalConditions = null);`

## User Impact
I've encountered a scenario where I need to read/write a property value to the project file for some non-standard dimensional conditions (`"$(RunConfiguration)=='Default'"`) within an intercepting value provider.

I'm able to write just fine using the API mentioned above, but to read from the project file I currently need to use [IProjectLockService](http://index/?rightProject=Microsoft.VisualStudio.ProjectSystem&file=Core%5cProjectLock%5cIProjectLockService.cs&line=96) which allows me to directly parse the xml.

This works fine for now, but it would be much simpler if we could just call Get(Un)EvaluatedPropertyValueAsync with dimensional conditions.