Trading - code improvements

[adderpositive]

Description

• tradingThunks vs tradingThunk.test. Same for buyThunks vs buyThunk.test
• improve test description according convention (test(trading): common functions #16913 (review))
• Consider to rewrite loadInvityData as a thunk.
• refactor to createSlice
• process feedback chore(trading): move buy trading part to suite-common #16866
• should call processResponseData with response and save trade is flaky (mocked date)

Related

Follow up #16518