[Meta] Port drupal.org's solr search functionality to D7

Related Tasks

1. #1700572: Manually test all existing ApacheSolr functionality in D6 to determine what, if anything, is still broken

Related Modules

There are several modules responsible for all the search capabilities on www.drupal.org:

1. https://drupal.org/project/drupalorg (drupalorg_search.module): {branch = origin/1548064-support-new-apachesolr} Also see #1548064: Upgrade drupalorg to support 6.x-3.x version of Apachesolr (Prep for D7 d.o)
2. https://drupal.org/project/drupalorg_crosssite {branch = origin/1549374-support-new-apachesolr}
3. https://drupal.org/project/project_solr {branch = origin/6.x-3.x}

Meta list of to-dos

This is a meta list of all the things which need to be done in order to get us there. Each of these needs to be turned into a task ticket within it's own respective module and moved upwards into the related tasks section, then deleted from this section.

Essential:

- Create meta type field for solr

- Index meta type content in solar

- Get meta type filtering to work

- Get search form meta type filtering to work

- Get search form meta type filtering to correctly auto-populate

- Create Sidebar block for meta type filtering

- Ensure meta type filtering is exclusive (single meta type filter at all times)

- Add "All" selection for meta type filtering

- Ensure meta type filtering displays full count, disregarding meta type filters

- Position meta type filter block

- Get general search sorting block to work

- Place general search sorting block

- Ensure special project fields are indexing (release, build, install)

- Ensure all necessary filters are present for project filtering (themes, modules, distributions)

-- Categories (modules only)

-- Compatibility

-- Status

-- Search (project pages only)

-- Sorts

--- Last release

--- Last build

--- Most installed

- Place meta-type specific block (modules & themes searches; modules, themes & distributions pages)

- Ensure project pages work (modules, themes, distributions)

- Ensure "new
" block is working

- Place "new
" block

- Ensure "most installed" block is working

- Place "most installed" block

- Suppress core search

- Suppress search tabs

Others?:

- Add distribution to meta type indexing

- Solr-ize issue queues (Probably won't happen prior to initial D7 launch)