Create @uifabric alias packages

[ecraig12345]

As part of the version 8 release, we're renaming our @uifabric packages to the @fluentui scope (see #13384).

For the following packages which are used by the suite, we'll add @uifabric aliases (which re-export the @fluentui version) so that partners who depend on multiple suite versions won't get multiple versions of all the dependency packages.

• @uifabric/file-type-icons
• @uifabric/foundation
• @uifabric/icons
• @uifabric/merge-styles
• @uifabric/react-hooks
• @uifabric/set-version
• @uifabric/styling
• @uifabric/utilities

For each of these packages, the alias package will be set up as follows:

• Located somewhere like /packages/aliases/<pkg-name>
• Depends on the corresponding @fluentui package and moves in lockstep with it (add beachball config to ensure this)
• Contains the same top-level files as the real package (re-exporting the real versions)

This should ideally be done pre-beta but could slip to early in the beta period if needed.

[ecraig12345]

Trying to handle package renames and getting rid of major-lockstep at the same time turned out to be too complex, so we will be continuing with major-lockstep for now and NOT making any alias packages. However, we will likely provide a codemod to help with renames (see #15661).