Explicitly return service response types

[grod220]

With the services we implement (in /packages/services), the return type of many of these method implementations return a plain javascript object. Example:

web/packages/services/src/view-service/gas-prices.ts

Lines 32 to 34 in ecc548e

	return {
	gasPrices,
	altGasPrices,

The challenge is that it is not typesafe and can lead to bugs such as #1626

Task: Convert all return types in our service method impls to the explicit return type of the response. Example:

-  return {
+  return new GasPricesResponse({
    gasPrices,
    altGasPrices,
-  };
+  });

This way, invalid fields will not be allowed and the typescript compiler will throw.