Adds radio buttons to switch the award year

[TheDancingClown]

📝 A short description of the changes

• Adds 3 new radio buttons to change the award year on admin/form_answers#index - 'Current year', 'All years' and 'Other'.
• Clicking 'Other' shows the existing years dropdown.
• Selecting 'Current Year' or 'All years' gets the form_answers#index passing the year param by using the data-url set in the view.
• On admin, all years are selected as default, but on assessors current year is default.
• Adds help copy to the search bar and changes the search icon to white on grey background.

🔗 Link to the relevant story (or stories)

• https://app.asana.com/0/1200504523179345/1207701977274862/f

Deployment implications

• None

✅ Checklist

• Features that cannot go live are behind a feature flag/env var or specify deploy date and open PR as draft
• I have checked that commit messages make sense and explain the reasoning for each change
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• I have squashed any unnecessary or part-finished commits

🖼️ Screenshots (if appropriate - no PII/Prod data):

[Lubosky]

Added some comments related to small tweaks but otherwise good 👍