File Nesting: Investigate file nesting performance impact on non-web projects

[swesonga]

File nesting code showed up in some traces when loading large solutions. This issue will track that investigation.

[drewnoakes]

Relates to AB#1256003.

[brian-pickens]

Does this mean that File Nesting won't be available until the next major release of visual studio?

[IanKemp]

What is the progress on this issue? Has it been corrected for VS 17.1/2022 Preview? @MiYanni @swesonga