fix(NODE-5801): use more specific key typing for multiple KMS provider support

Author: addaleax

src/client-side-encryption/providers/index.ts

@@ -122,34 +122,31 @@ export interface KMSProviders {
    * Configuration options for using 'aws' as your KMS provider
    */
   aws?: AWSKMSProviderConfiguration | Record<string, never>;
+  [key: `aws:${string}`]: AWSKMSProviderConfiguration | Record<string, never>;
 
   /**
    * Configuration options for using 'local' as your KMS provider
    */
   local?: LocalKMSProviderConfiguration;
+  [key: `local:${string}`]: LocalKMSProviderConfiguration;
 
   /**
    * Configuration options for using 'kmip' as your KMS provider
    */
   kmip?: KMIPKMSProviderConfiguration;
+  [key: `kmip:${string}`]: KMIPKMSProviderConfiguration;
 
   /**
    * Configuration options for using 'azure' as your KMS provider
    */
   azure?: AzureKMSProviderConfiguration | Record<string, never>;
+  [key: `azure:${string}`]: AzureKMSProviderConfiguration | Record<string, never>;
 
   /**
    * Configuration options for using 'gcp' as your KMS provider
    */
   gcp?: GCPKMSProviderConfiguration | Record<string, never>;
-
-  [key: string]:
-    | AWSKMSProviderConfiguration
-    | LocalKMSProviderConfiguration
-    | KMIPKMSProviderConfiguration
-    | AzureKMSProviderConfiguration
-    | GCPKMSProviderConfiguration
-    | undefined;
+  [key: `gcp:${string}`]: GCPKMSProviderConfiguration | Record<string, never>;
 }
 
 /**