LF-4256 Old consent version is shown after setting has_consent to false

[kathyavini]

Description

This PR:

• Cherry-picks @SayakaOno's commits from LF-4240: April 2024 data policy updates (Version 6: May 31, 2024) #3217 that created and used the new consent version constant
• Uses that constant to check against the database stored consent version (this is fundamentally how the release badge works as well)
• has_consent as stored in the Redux store now takes into account consent version mismatch: LF-4256 (2): Old consent version is shown after setting has consent to false #3224

Notes:

• It is the routes file check that had been triggering the need to re-consent upon first route change
• We could instead logout() instead of routing to /consent -- it would probably introduce a bit of complication and being more careful where that routing happens -- but I left it as is because I don't think the user experience is that bad
• In the future the only change necessary will be updating the consent version in the constants file along side the updated text

Jira link: https://lite-farm.atlassian.net/browse/LF-4256

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

• Passes test case
• UI components visually reviewed on desktop view
• UI components visually reviewed on mobile view
• Other (please explain)

This demonstrates how the re-consenting is required. It should be merged together with the changes to the consent text (as will happen in the patch PR) for the timing to be correct.

Checklist:

• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• The precommit and linting ran successfully
• I have added or updated language tags for text that's part of the UI
• I have added "MISSING" for all new language tags to languages I don't speak
• I have added the GNU General Public License to all new files

[Duncan-Brain]

Looks promising nice solution you two! So happy we don't have to add migrations anymore!