Remove `name` from `ModuleMetadata`

[srujzs]

Today, DDC emits metadata about the modules it emits, including the name, URI, library metadata, source mappings, and more.

With the new library bundle module format (which will become the only format), library bundles do not have a name associated with them. Today, we emit unused for the name:

sdk/pkg/dev_compiler/lib/src/js_ast/nodes.dart

Line 372 in baef07c

name: 'unused',

. This will be a breaking change and downstream uses need to be refactored once we move off of all the other module formats (note that this can't happen sooner since require.js needs module names). There is support for versioning today, so we should leverage that:

sdk/pkg/dev_compiler/lib/src/kernel/module_metadata.dart

Line 12 in baef07c

class ModuleMetadataVersion {

.