Add support for VB and F# projects in az webapp up

[anthonychu]

Extension name (the extension in question)

webapp

Description of issue (in as much detail as possible)

az webapp new currently only looks for *.csproj to determine if it's a .NET project. It should also look for *.vbproj and *.fsproj.

[panchagnula]

@anthonychu i am not closing this since these are languages that we are currently not planning on supporting