Add index file to application and controller - Closes #5494

[ManuGowda]

What was the problem?

This PR resolves #5494

How was it solved?

• Added index files

How was it tested?

• Updated unit tests

[ishantiw]

We have 3 different imports from controller, maybe we can export ActionInfoObject and InMemoryChannel as well from the controller/index file?

lisk-sdk/framework/src/application/application.ts

Line 41 in dc431dc

import { Controller } from '../controller';

lisk-sdk/framework/src/application/application.ts

Line 47 in dc431dc

import { InMemoryChannel } from '../controller/channels';

lisk-sdk/framework/src/application/application.ts

Line 53 in dc431dc

import { ActionInfoObject } from '../controller/action';