The vscodium project is now releasing artifacts with slightly different naming: `VSCodium-darwin-${VSCODIUM_VER}.zip` is now `VSCodium-darwin-x64-${VSCODIUM_VER}.zip`. This is likely due to arrival of the new ARM-based macs. In any case, it does mean that we need to update `update-vscodium.sh` to pull the correct artifact down.
Split up the vscode update.sh into separate vscode/vscodium update
scripts. Recently the versions of vscode and vscodium have diverged (see
VSCodium/vscodium#501), meaning that the updates for one package fail
while the other succeeds. This PR splits up the update scripts so that
one can be run with out the other and vice-versa.