More test code

src/discordmessageprocessor.ts

src/presencehandler.ts

src/store.ts

test/mocks/channel.ts

test/mocks/collection.ts

test/mocks/discordclient.ts

test/mocks/guild.ts

test/mocks/member.ts

test/mocks/presence.ts

test/mocks/user.ts

test/test_discordbot.ts

test/test_discordmessageprocessor.ts

test/test_matrixmessageprocessor.ts

test/test_matrixroomhandler.ts

test/test_presencehandler.ts

test/test_usersyncroniser.ts