Preview .NET 7 compatibility

[johnnyr0x]

Day 1 compatibility with .NET 7

Describe the Enhancement

Evaluate .NET 7 early by using the preview version. This request is not the same as issue 525. Instead, focus on evaluating and implementing the changes needed for the .NET buildpack and tests by using the preview version that is available now so we can release .NET 7 buildpack support in November, shortly after 7 is released.

Possible Solution

Start a new branch that merges in the .NET 7 preview to confirm buildpack and sample compatibility with .NET 7

Motivation

It can take quite a while to support new versions. Let's get ahead of the curve to support users more quickly.

[sophiewigmore]

This has been done and implemented!