Expand list of exceptions for methods calling into GetFullPath

# Expand list of exceptions for methods calling into GetFullPath

## General

The API reference does not in all cases provide a complete list of exceptions of methods that call into GetFullPath. A complete list is provided in the [Directory.GetParent](https://review.docs.microsoft.com/en-us/dotnet/api/system.io.directory.getparent) method. The same exception information should be incorporated into the documentation of the other methods that call into GetFullPath.

Note, incidentally, that SecurityException is a .NET Framework-only exception. The documentation should be revised to reflect that as part of this work.

For a discussion of the issue, see PR dotnet/docs#3971.

//cc @mriehm @mairaw @JeremyKuhne @pjanotti