Resolve "Projects should be searchable"

Features

• Add search functionality to projects
• Add ordering functionality to projects (creation date, alphabetical, grouped by company)
• Add filtering functionality to projects (filter by company)
• Separate Project Preferences into a separate route, page and controller
• Add functionality to reliably test Elasticsearch-based results

Improvements

• Improve code style by adding comments and applying small refactorings
• Optimize and simplify theme search
• Skip unnecessary loading of all themes for the show/update/new pages of themes
• Adapt master market related code to move towards master market separation per programme
• BREAKING: Include environment in Elasticsearch index names to prevent tests overwriting development/production indices

Bug fixes

• Fix themes search not showing results in order of relevance

Closes #196 (closed)