Add command for converting multiple solutions to solution filters

[BalassaMarton]

This would be useful when converting a multi-solution repo to a single-solution monorepo with solution filters.

Command syntax

please create solution filters --from <ExistingSolutions> --target <TargetSolution>

ExistingSolutions is a globbing pattern that selects the existing .sln files from the current working directory.
TargetSolution is a .sln file name.

Expected behavior

• If TargetSolution does not exist, create it.
• Then, for each .sln file in ExistingSolutions as sln:
  • Add the projects from sln to TargetSolution under a solution directory generated from the name of sln
  • Create a solution filter from sln that uses TargetSolution as the base
  • Delete sln