Add support for femto

[MangelMaxime]

If FablePackageType is set to binding and one of the target is supported by Femto then we could try to run femto to validate that the requested version is supported.

In such a case, if femto metadata are missing we can generate a warning inviting people to add these metadata.

[MangelMaxime]

Research about running a tool from MSBuild:

• https://stackoverflow.com/questions/74488608/how-to-run-dotnet-tool-in-prebuild-phase-of-an-sdk-project

• We will probably need to use MSBuild task/target to detect if femto is available or not.

  Check if we can set an MSBuild property/variable from a target and then from another dependants target access that property to conditionally execute it.