MAINT-5687: Remove old webkit from the make files and the repo.  Ensure that it is no longer meaningfully referenced.

Add code in viewer_manifest.py to create a symlink for second copy of CEF framework vs copying in second version

Add commands to move CEF runtime files to right place and fix up media_plugin_cef with install_name_tool (note, this generates 2 copies of CEF framework - will fix later)

point to new cef tpl with right headers, update cmaake and viewer_manifest logic to copy files to right place

Generalize Copy3rdPartyLibs.cmake to eliminate some clone-and-tweak redundancy.

The former is the real .so, to which libalut.so is only a symlink. We were
packaging the symlink without including its target.
(This appears to have changed since our last Vivox drop for Linux.)

into eventual viewer package -- instead of finding them in the viewer build
tree. Also update Windows to current slplugins package build.

The .dylib files in the Linux Vivox package were erroneous to start with;
while the affected changeset bypassed copy errors, it too was wrong. Now that
the Linux Vivox package contains Linux .so files, revert to the correct
filenames to copy.

To this point, we've been failing the build with a Python OSError traceback,
which is less than ideal.

This only applies to the Windows package so far, because so far only the
Windows package exists.

Ensure that AUTOBUILD is always in native path syntax on every platform.
Remove local build.sh logic to infer AUTOBUILD: either the generic build.sh
has set it properly, or scream for help.
Since cygwin bash scripts need a cygwin-syntax path to autobuild, convert to a
local 'autobuild' variable using shell_path.
Remove kludges in other languages involving cygdrive twiddling.

Restore Unicode path to viewer_manifest script - apparently we use the Unicode version of NSIS, not the one from the NULLSOFT site

'raisef' is not a Python statement.

reorder finalizing for OSX so that the signature is applied to the app after copying into the dmg; preserves extended attributes