label visibility for exposed numeric and date filter when using single and multi value filter

Problem/Motivation

When exposing a views filter on a numeric or date field the labels shown are missing or not placed in a logical order. Also there is no containing span to group operator and input field(s). This is related to / extends #2480719: Missing label and description for exposed numeric filter when using 'between' filter

Filter that has no exposed operator:

Filter that has an exposed operator with a single input value:

The label and description are not rendered correctly. There is no span surrounding the two elements for styling / keeping them together. The operator filter element label "Operator" is rendered in the same style as a separate filter.

Filter that has an exposed operator with multiple input values:

The label and description are rendered on the first of the two inputs. There is no span surrounding the three elements for styling / keeping them together. The operator filter element label "Operator" and the "And" label are rendered in the same style as a separate filter. This is the behaviour after applying the patch for #2480719: Missing label and description for exposed numeric filter when using 'between' filter. The Language filter is shown for reference how the exposed filter looks when showing a row of filters.

Proposed resolution

Do what was done in D7 Views.

Single

Single operator exposed

Multiple

Multiple operator exposed

Remaining tasks

1. Update tests
2. Update patch

User interface changes

Add the label like it is in the not-exposed filter.

API changes

None.