Tests: gate logging behind DEBUG env var (#4903)

* Add `DebugLogger` type for logging matrix-js-sdk to `debug`

* unit tests for DebugLogger

* Use `DebugLogger` in some tests

* Use `DebugLogger` in rust-crypto.spec

* test-utils: silence some logging

src/matrix.ts

@@ -109,6 +109,7 @@ export { IdentityProviderBrand, SSOAction } from "./@types/auth.ts";
 export type { ISSOFlow as SSOFlow, LoginFlow } from "./@types/auth.ts";
 export type { IHierarchyRelation as HierarchyRelation, IHierarchyRoom as HierarchyRoom } from "./@types/spaces.ts";
 export { LocationAssetType } from "./@types/location.ts";
+export { DebugLogger } from "./logger.ts";
 
 let cryptoStoreFactory = (): CryptoStore => new MemoryCryptoStore();