IDEAS: Show search results quantity from idea body on each idea card

[BeccaMelhuish]

Sub-issue of #1528, add the number of results for the searched word found within each idea, as per this design:

However, please use the text 'Results: X' rather than 'X results found'.

Ideally, only show this 'results' label for the search results found in the body of the idea, not for those in the title.

So for example, someone searches for 'happy':

Idea #1 has the word 'happy' in the title only - don't show any results label for the idea
Idea #2 has the word 'happy' in the title once, and 4 times in the body - show 'Results: 4'
Idea #2 does not have the word happy in the title, but has it 4 times in the body - show 'Results: 4'

However, @DiverVM if doing it this way makes it more complex somehow, please let me know and let's discuss before you go ahead :)

[BeccaMelhuish]

Moving this to UX research column as we decided not to do it yet - not high priority as it works fine without it. If later we find it is causing UX issues and have funding to fix it, we can do so.