Fix Ampersand Issue When Rendering Plan.title

[aaronskiba]

Fixes https://github.com/DMPRoadmap/roadmap/issues/3348

• https://github.com/DMPRoadmap/roadmap/issues/3348

Changes proposed in this PR:

• Use sanitize() on Plan.title to enable proper rendering of ampersands
• Use .gsub(/&/,'&') on Plan.title to enable proper rendering of ampersands in downloaded .txt files of plans
• Change '- add contributor' to '- add research output' for appended browser tab title in app/views/research_outputs/new.html.erb

[aaronskiba]

It looks like Rubocop is failing because the rubocop gem was updated, but the newly found rubocop errors still need to be addressed.