R1:fcf64953f093

Migate more of Pholio to Modular Transaction

Summary: Another Franken-transaction. Adds transactions for ImageName and MockName. Adds transaction-level validation for presence of mock name; removed same from edit controller. Removes `PholioTransaction::getRemarkupBodyForFeed()`, which appears to be dead code since that method isn't defined on any other types.

Test Plan: made a bunch of changes to pholio mocks and images and observed expected results

Reviewers: #blessed_reviewers, epriestley

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