Refactor Relationship Calculator and Add a Searchbar

[stevenyoungs]

Refactor the relationship calculator tool

• now based on SelectPerson
  previously the calculator had it's own implementation of a person tree
• BaseSelector and SelectPerson classes updated to support modal or modeless operation. All existing use use remains modal
• Relationship calculator now includes a search bar to aid finding the other person
• supports changes in active person after the tool is opened
• supports changes in families and recalculates the relationship
• handles database change (the current tool crashes)

Related discourse discussion, including user request: https://gramps.discourse.group/t/adding-search-bar-to-select-person-dialog/6845/10?u=stevey

[stevenyoungs]

Steps to crash the existing relationship calculator tool

1. open the example database
2. open the relationship calculator tool
   no need to click anything in the tool
3. close the database
   the relationship calculator window is still displayed with all people listed
4. expand a surname in the relationship calculator window

An error similar to the below will be generated

36104: ERROR: grampsapp.py: line 188: Unhandled exception
Traceback (most recent call last):
  File "C:\Program Files\GrampsAIO64-5.2.3\gramps\gui\views\treemodels\treebasemodel.py", line 962, in do_get_value
    val = self._get_value(node.handle, col, node.secondary)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Program Files\GrampsAIO64-5.2.3\gramps\gui\views\treemodels\treebasemodel.py", line 979, in _get_value
    data = self.map(handle)
           ^^^^^^^^^^^^^^^^
  File "C:\Program Files\GrampsAIO64-5.2.3\gramps\gen\db\generic.py", line 1734, in get_raw_person_data
    return self._get_raw_data(PERSON_KEY, handle)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Program Files\GrampsAIO64-5.2.3\gramps\plugins\db\dbapi\dbapi.py", line 1002, in _get_raw_data
    self.dbapi.execute(sql, [handle])
  File "C:\Program Files\GrampsAIO64-5.2.3\gramps\plugins\db\dbapi\sqlite.py", line 136, in execute
    self.__cursor.execute(*args, **kwargs)
sqlite3.ProgrammingError: Cannot operate on a closed database.

In Windows AIO at least, there is a never ending stream of errors. The only escape is to kill the gramps process.