A schematic has been added that will allow the generation of environment files
for all existing configurations within a project. The `fileReplacements` option
will also be setup to allow the replacement of the appropriate environment file.
Environment files themselves do not provide any special behavior beyond
that of other application TypeScript files and rely on the `fileReplacements`
option for build-time behavior. The schematic will skip generating environment files
for configurations that already have an appropriately named environment file. The
`fileReplacements` option addition will also be skipped if an appropriate entry
is already present.
