Metatags in views override by path configuration

I managed to solve this using setting "META TAGS" in view edit page and changing meta fields there.

Are we suggesting that the Metatag Context (By path) should have higher priority? In other words, if we create a context by path to set metatags, that should override Metatag views?

I have changed the hook from page_build() to page_alter() which is the same hook used by Metatag Views

Then I make sure that Metatag Context always runs last

function metatag_module_implements_alter(&$implementations, $hook) {
  if ($hook == 'page_alter') {
    // Run metatag_context_page_alter() last.
    $group = $implementations['metatag_context'];
    unset($implementations['metatag_context']);
    $implementations['metatag_context'] = $group;
  }
}

Also, I am not sure why we were using 'global' as instance. I think it makes sense changing it to 'by_path'.

    $page[$region]['metatags']['by_path'] = $metatags;

Here is how I tested this:

1. Create a view that has a page
2. Create a Metatag Views configuration
3. Visit that view and check if the metatags for the views come from the settings above
4. Create a Metatag context by path (same as used on view)
5. Visit the view again and check that the metatags come from the settings above

Patch here to be reviewed

Few more fixes and tests updated

This needs to be rerolled.

Re-rolled the patch #6.
I didn't have time to do the tests, please review the patch and if everyone is happy we can port the tests from #6

If you are wondering why I removed hook_preprocess_html(), it's because I don't see any reason for it to be there.
I assume it was an attempt to override the page title, please correct me if I am wrong.
I tested the code without this hook and I was able to override page title with no problems.

Committed. Thanks!