Projects: serialize `enabled` and `hidden` as boolean

Dependencies

• [2] 7RRDNLP3 Add homepage to Projects schema
• [3] BXHG3HYL When renaming a jobset, add a redirect from the old name
• [4] W5OAZWPD Drop the errorMsg column in the Jobs table
• [5] 7ECJWNVX Cleanup Project model
• [6] NZXX6PLD Remove the Jobs table
• [7] BMGYDRNK jobsetevals: refer to jobset by ID
• [8] N74SRHS6 Remove the "releases" feature
• [9] 6WRGCITD Enable declarative projects.
• [10] MB5INTIQ Normalize nixexpr{input,path} from builds to jobsetevals.
• [11] YU6CND7C Remove support for views
• [12] PCD3ZH6Z Partially revert 1c20cfdf2403feb78cef515faf15c04d5c9f17bd
• [13] KSBB33RE Add a dashboard
• [14] IGR322YP sql: Generate models from postgresql
• [15] T5BIOVJE Add support for tracking custom metrics
• [*] X27GNHDV * Basic job info in the database.

Change contents

• edit in src/lib/Hydra/Schema/Projects.pm at line 255
  [2.109]→[3.264:301](∅→∅),[3.264]→[3.264:301](∅→∅)
  − "enabled",

  − "hidden",
• edit in src/lib/Hydra/Schema/Projects.pm at line 256
  [3.317]

  [3.317]
  + ],

  + boolean_columns => [

  + "enabled",

  + "hidden"