ShellPkg: UefiShellLib: drop wrong PathLib library class dependency

ShellPkg: UefiShellLib: drop wrong PathLib library class dependency

SVN r16601 ("MdeModulePkg, MdePkg, NetworkPkg, OvmfPkg, PerformancePkg,
ShellPkg: Library Migration.") incorporated ShellPkg/Library/BasePathLib
into MdePkg/Library/BaseLib. BasePathLib had been the only instance of
library class PathLib.

Even so, SVN r16606 ("ShellPkg: allow creating of files to create required
directory path") added a PathLib dependency to
"ShellPkg/Library/UefiShellLib/UefiShellLib.inf".

This breaks edk2 platforms that build the "new" UEFI shell from source.
Undo the wrong dependency.

Similarly, update the <Library/PathLib.h> #include directive to
<Library/BaseLib.h> (example function prototype: PathRemoveLastItem()).

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16609 6f19259b-4bc3-4df7-8a09-765794883524