Add Ask FT button to o-header

[Ventzy]

Describe your changes

• Add ASK FT button linking to https://ask.ft.com/ in o-header:
  • Top header - visible on screen size L and up
  • Drawer - visible on smaller screens, same as search in the drawer
  • Sticky header - visible on screen size L and up
• Add new optional showAskButton prop in THeaderOptions to control ASK FT button rendering. By default, the button is not rendered
• Add showAskButton prop in o-header stories

Ask FT button was previously added in dotcom-ui-header and it is currently active on ft.com home and article pages. This PR adds the same in o-header and will be followed with dotcom-ui-header changed to align with o-header. For reference - this is the PR in dotcom-ui-header which has added the button there - https://github.com/Financial-Times/dotcom-page-kit/pull/1031

Please review the PR inline comments. I need confirmation if specific approaches taken are fine or adjustments are needed.

Issue ticket number and link

Ticket: https://financialtimes.atlassian.net/browse/ARP-251

Link to Figma designs

https://www.figma.com/design/G0vA3biIFmIeXa0bB3bqWW/ARP%3A-Ask-FT?node-id=6579-37992&t=MyjE38aot5OS5vmH-4

Storybook screenshots

Top

Sticky

Drawer desktop

Drawer mobile

Checklist before requesting a review

• [ ] I have applied percy label for o-[COMPONENT] or chromatic label for o3-[COMPONENT] on my PR before merging and after review. Find more details in CONTRIBUTING.md
• [ ] If it is a new feature, I have added thorough tests.
• [ ] I have updated relevant docs.
• [ ] I have updated relevant env variables in Doppler.