feat(discovery): supports discovering projects from MSBuild Project files (i.e traversal SDK)

[leonardochaia]

This PR deprecates the --solution-file-path argument being replaced by the new --filter-file-path.

The --solution-file-path has not yet being removed, but is being discontinued. Using --solution-file-path is equivalent to using --filter-file-path

The --filter-file-path allows us to support multiple file types based off the extension of the file.
For example:

dotnet affected --solution-file-path ./my-solution.sln
# should be replaced by
dotnet affected --filter-file-path ./my-solution.sln

# new supported type: traversal project sdk:
dotnet affected --filter-file-path ./my-traversal-project.proj

In the future we could implement other file formats, like json or yaml

Fixes #87