Msbuild: Add GetFileHash and VerifyFileHash tasks to XSD (for IntelliSense)

[rainersigwald]

_Reported by @japj in https://github.com/Microsoft/msbuild/pull/3999#issuecomment-458141311._

3398 exposed two new tasks, but they're not exposed to Visual Studio's autocompletion because they're not mentioned in the XSD used for that.

They need an entry like

https://github.com/Microsoft/msbuild/blob/966cdf2ac602e359530ad63f608e6cbba9c9fd0f/src/MSBuild/Microsoft.Build.CommonTypes.xsd#L2198-L2211

but with the right inputs/outputs.

[santoshyadavdev]

Hi @rainersigwald ,

Will work on it, first time contributor here so may need some help.

[rainersigwald]

Sounds good! Removing up-for-grabs; this is @santoshyadav198613's.

Let us know if you run into trouble!

[santoshyadavdev]

HI @rainersigwald ,

Just one help, should i add the schema at the end in the file, or should i add in it TASKS section like others.
Is there any pattern we follow here.

[rainersigwald]

I'd say in that TASKS section, sorted alphabetically by task name.

[santoshyadavdev]

Cool sounds good will make the changes accordingly.