Placeholder text support for level short/long instructions and authored hints

[smusoke]

What:
This PR was worked on simultaneously and merged its branch into this one. Giving us authored_hint support for (virtually)free!

• Updated sync-in.rb to parse short_instructions, long_instructions, and authored_hints for placeholder text block's.
• Added the short/long instruction & authored hint placeholder text translation support into the blockly model.
• Unit test for blockly.rb.

Why: This will allow for placeholder text blocks to be integrated into the translation pipeline and translated for these level properties moving forward.

Links

• jira ticket: FND-1771

Testing story

• Locally tested that placeholder text within short/long instructions and authored hints should be included during sync-in
• Ran short test script that called the new localized_blockly_in_text method on every level's relevant markdown property.

Level.all.each do |l|
  if l.is_a? Blockly
    l.localized_short_instructions
    l.localized_long_instructions
    l.localized_authored_hints
  end
end

• Created unit test for blockly model
• Locally tested dummy placeholder translations

Deployment strategy

Merge after #43573

Follow-up work

Similar updates to provide support for validation text.
https://codedotorg.atlassian.net/browse/FND-1771

PR Checklist:

• Tests provide adequate coverage
• Privacy and Security impacts have been assessed
• Code is well-commented
• New features are translatable or updates will not break translations
• Relevant documentation has been added or updated
• User impact is well-understood and desirable
• Pull Request is labeled appropriately
• Follow-up work items (including potential tech debt) are tracked and linked

[daynew]

Looks good, just a minor comment about testing.

[daynew]

I don't think it would be too much hassle to add long_instructions and short_instructions to the level we are creating in this test, and then call them to verify that those properties are actually get translated.

[smusoke]

Added 👍

[daynew]

Looks even better now!