UX/UI refactor on the center and stations filters

[JohnMwashuma]

User story

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This can be observed and tested on the form-results view,
though the proposal should apply for all table filters that have drilldown semantics.

Filters of interest on this view:
- centers filter: select center(s) and auto-selects stations that belong to selected centers.
- stations filter: further refine filter based on stations that belong to selected centers.

Current behavior is that:

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When center(s) is/are selected, stations that belong to the center(s) are also automatically selected
.In the stations filter, the sample space of options for stations still remain the same, i.e.
it stiill includes all stations in the system.

A side effect is that a user can add a station filter that does not belong to one of the selected center.

in steps:

1. click center filter
2. select 11002 center
3. notice only 2 stations have been preselected in the stations select
4. click on the stations filter.
5. notice the full list of options shown include all stations in the system.
6. A user is at liberty to select any other stations regardless of whether they belong to selected center(s)

The proposed change:

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When a center(s) is/are selected, the possible sample space of station options that can be
selected in the stations filter is limited to just stations that belong to the selected centers.

in steps:

1. click the center filter
2. select 11002 center
3. 2 stations should be auto-selected in the stations filter select
4. click on the stations filter
5. The full list of stations options should just be 2 stations. The 2 stations that belong to the 11002 center.

Note: the output in the steps above is dependent on the data currently on stage and might with time
depending to data changes in the staging db.