Use VS Code packaging for releases (#7721)

* Allow setting the VS Code build target

For the NPM package (and tests, at least for now), we will still use
linux-x64, but this is going to allow using the platform build targets
for our standalone releases so we can avoid having to copy all the
packaging steps (like cleaning up modules).

This does mean that the NPM package when installed will be missing those
cleanup steps.  Possibly we can try to break out the packaging step into
a something that can be ran standalone (which will also require
installing dev dependencies like gulp) but not sure how much work this
would be.

* Preserve dependencies for e2e tests

To avoid having to install them again.

Also moved an env block to the root of the  job.

* Refactor releases to use VS Code packaging

Instead of building the linux-x64 package, stripping the modules, then
installing them again, we build the correct target and use the modules
as they are.

This means we do not have to copy all the post-processing steps like the
ones that delete unnecessary modules.

For the NPM package we still publish the linux-x64 package (without
modules of course).  This means npm installations do not get that same
post-processing.

Another advantage of this is that we can run the release immediately
without having to wait for the build step, or on a commit that no longer
has a build artifact, since they all build individually now.  We could
try sharing the core-ci build step, but leaving that alone for now.

I also converted the macOS jobs into a matrix.

Deleted the CI readme because it was out of date and seemed to just
repeat what should be described in the scripts anyway.

Removed a section about Homebrew since we do not maintain that anymore.

It looks like there is no need to symlink node_modules.asar anymore.

ci/build/npm-postinstall.sh

@@ -23,17 +23,6 @@ symlink() {
   esac
 }
 
-# VS Code bundles some modules into an asar which is an archive format that
-# works like tar. It then seems to get unpacked into node_modules.asar.
-#
-# I don't know why they do this but all the dependencies they bundle already
-# exist in node_modules so just symlink it. We have to do this since not only
-# Code itself but also extensions will look specifically in this directory for
-# files (like the ripgrep binary or the oniguruma wasm).
-symlink_asar() {
-  symlink node_modules node_modules.asar
-}
-
 # Make a symlink at bin/$1/$3 pointing to the platform-specific version of the
 # script in $2.  The extension of the link will be .cmd for Windows otherwise it
 # will be whatever is in $4 (or no extension if $4 is not set).
@@ -145,7 +134,6 @@ vscode_install() {
     return 1
   fi
 
-  symlink_asar
   symlink_bin_script remote-cli code code-server
   symlink_bin_script helpers browser browser .sh