Create V2 for calculate-state-pension smart answer

We'll need a lot of the work here to go out for fact check before it
goes live. For this reason we're adding a V2 -- likely to be merged
into the main (published) smart answer once fact check is complete.
Update copy for Q1 options
Show 'near state pension' age if between 4 months and 1 day of SP
Ask for NI years if older than 20 and picked 'amount' route
Check within four months and one day of pension date
Copy updates

- Inline NI link
- Add explanation on what the calculation is according to
- Titles for some sections when user has reached state pension age
Move block of content down
Additional copy changes involving 'more information' sections

Also made Pension Service claim line link bold instead of italic.
Use the correct -v2 flow
Update tests that now refer to four months and one day
Merge remote-tracking branch 'origin/july-14-state-pension-changes'