[FIX] web: on SearchPopup creation concat build context even if we have initial_ids

  On SearchPopupCreation, if we have initial_ids - 1st search_read() will be
  missing custom context defined on the field.

  1. defined view like this: <field name='my_many2one_field_id' context="{'test': 1}"/>
  2. in we expand the list of available item, name_search() has 'test' in context
  3. in we click on 'Search More', search_read() is missing 'test' in context
  4. if we change filter add/remove item, search_read() will have 'test' in context

  Step 3. is wrong, should also have 'test' in context
[FIX] web: on SearchPopup creation concat build context even if we have initial_ids

  On SearchPopupCreation, if we have initial_ids - 1st search_read() will be
  missing custom context defined on the field.

  1. defined view like this: <field name='my_many2one_field_id' context="{'test': 1}"/>
  2. in we expand the list of available item, name_search() has 'test' in context
  3. in we click on 'Search More', search_read() is missing 'test' in context
  4. if we change filter add/remove item, search_read() will have 'test' in context

  Step 3. is wrong, should also have 'test' in context
[FIX] web: set z-index of 9999 for autocompletion pane of search bar, to avoid being behind jquery ui dialogs. Besides, this pane should always be on top, therefore we can assume that setting 9999 will not have bad side effects