changes for first dotnet-scaffold release

[deepchoudhery]

dotnet-scaffold changes:

• adding dotnet-msidentity commands.
• dotnet-aspnet-codegenerator commands have additional --.
• dotnet-scaffold Program.cs calls into the CommandHandlers in Microsoft.DotNet.Tool.Program's CommandHandlers.

Previous help:

scaffold:
  dotnet scaffold [command] [-p|--project] [-n|--nuget-package-dir] [-c|--configuration] [-tfm|--target-framework] [-b|--build-base-path] [--no-build]

Usage:
  scaffold [options] [command]

Options:
  -p, --project <project>                        Specifies the path of the project file to run (folder name or full path). If not specified, it defaults to the current directory.
  -n, --nuget-package-dir <nuget-package-dir>    Specifies the NuGet package directory.
  -c, --configuration <configuration>            Defines the build configuration. The default value is Debug. [default: Debug]
  -tfm, --target-framework <target-framework>    Target Framework to use.For example, net46.
  -b, --build-base-path <build-base-path>        The build base path.
  --no-build                                     Doesn't build the project before running. It also implicitly sets the --no-restore flag.
  --version                                      Show version information
  -?, -h, --help                                 Show help and usage information

Commands:
  area <AreaNameToGenerate>                             Scaffolds an Area.
  controller                                            Scaffolds a Controller
  razorpage <RazorpageNameToGenerate> <TemplateName>    Scaffolds Razor pages.
  view <ViewNameToGenerate> <TemplateName>              Scaffolds a View
  identity                                              Scaffolds Identity

New help:

scaffold
  dotnet scaffold [command] [-p|--project] [-n|--nuget-package-dir] [-c|--configuration] [-tfm|--target-framework] [-b|--build-base-path] [--no-build] 

Usage:
  scaffold [options] [command]

Options:
  -p, --project <project>                      Specifies the path of the project file to run (folder name or full path). If not specified, it defaults to the current directory.
  -n, --nuget-package-dir <nuget-package-dir>  Specifies the NuGet package directory.
  -c, --configuration <configuration>          Defines the build configuration. The default value is Debug. [default: Debug]
  -tfm, --target-framework <target-framework>  Target Framework to use.For example, net46.
  -b, --build-base-path <build-base-path>      The build base path.
  --no-build                                   Doesn't build the project before running. It also implicitly sets the --no-restore flag.
  --version                                    Show version information
  -?, -h, --help                               Show help and usage information

Commands:
  --area <AreaNameToGenerate>                           Scaffolds an Area.
  --controller                                          Scaffolds a Controller
  --razorpage <RazorpageNameToGenerate> <TemplateName>  Scaffolds Razor pages.
  --view <ViewNameToGenerate> <TemplateName>            Scaffolds a View
  --identity                                            Scaffolds Identity
  --register-app                                        Register an Azure AD or Azure AD B2C app registration in Azure and update the project.
                                                        	- Updates the appsettings.json file.
  
  --unregister-app                                      Unregister an Azure AD or Azure AD B2C app registration in Azure.
                                                        	- Updates the appsettings.json file.
  
  --create-app-registration                             Create an Azure AD/AD B2C app registration in Azure.
  
  --update-app-registration                             Update an Azure AD/AD B2C app registration in Azure.
  

[sayedihashimi]

@deepchoudhery it looks good. I noticed some minor issues.

• Typo, missing a space, at "Target Framework to use.For example, net46."
• Remove period to the end of
  • "Scaffolds an Area."
  • "Scaffolds Razor pages."