Replace invalid variable characters for import name (facebook#4293)

Summary:
Closes: facebook#4294

When using provided variables, with ESM, the Relay compiler incorrectly assumes that the module path can also be reused for the default import name.

This is not valid Javascript as variables cannot use '.' or '-' characters.

To fix, simply replace '.' and '-' with underscores.

Before:
```
import include-can-edit-providers-three.relayprovider from './../include-can-edit-providers-three.relayprovider';
import include-can-edit-providers.relayprovider from './../include-can-edit-providers.relayprovider';
const providedVariablesDefinition: ProvidedVariablesType = {
  "__relay_internal__pv__includecaneditprovidersrelayprovider": include-can-edit-providers-three.relayprovider,
  "__relay_internal__pv__includecaneditprovidersthreerelayprovider": include-can-edit-providers.relayprovider
};
```

After:
```
import include_can_edit_providers_two_relayprovider from './../include-can-edit-providers-two.relayprovider';
import include_can_edit_providers_relayprovider from './../include-can-edit-providers.relayprovider';
const providedVariablesDefinition: ProvidedVariablesType = {
  "__relay_internal__pv__includecaneditprovidersrelayprovider": include_can_edit_providers_relayprovider,
  "__relay_internal__pv__includecaneditproviderstworelayprovider": include_can_edit_providers_two_relayprovider
};
```

I'm unfamiliar with Rust so am unsure if there is a better approach.

Pull Request resolved: facebook#4293

Reviewed By: tyao1

Differential Revision: D46360937

Pulled By: captbaritone

fbshipit-source-id: bb8383f0fd97a8510ccf4dff29eefbaddee33be1

compiler/crates/relay-codegen/src/build_ast.rs

@@ -1813,11 +1813,14 @@ impl<'schema, 'builder, 'config> CodegenBuilder<'schema, 'builder, 'config> {
  )
  };
 
+ let variable_name =
+ (provider.original_variable_name.to_string() + "_provider").intern();
+
  Some(ObjectEntry {
  key: def.name.item.0,
  value: Primitive::JSModuleDependency(JSModuleDependency {
  path: provider_module,
- import_name: ModuleImportName::Default(provider.module_name),
+ import_name: ModuleImportName::Default(variable_name),
  }),
  })
  })