MVC doesn't work on FIPS-compliant machines

[Eilon]

Related to aspnet/Antiforgery#95

Bad codes:

• Mvc/src/Microsoft.AspNetCore.Mvc.TagHelpers/Internal/FileVersionProvider.cs

  Line 114 in a78f77a

  using (var sha256 = SHA256.Create())

• Mvc/src/Microsoft.AspNetCore.Mvc.TagHelpers/Cache/CacheTagKey.cs

  Line 154 in 341430e

  using (var sha = SHA256.Create())

[NTaylorMullen]

PR is ready to go in. Waiting for patch-approved.