fix(select): improve focus/blur handling on iOS

[Splaktar]

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• Tests for the changes have been added or this is not a bug fix / enhancement
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PR Type

What kind of change does this PR introduce?

[x] Bugfix
[ ] Enhancement
[ ] Documentation content changes
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Infrastructure changes
[ ] Other... Please describe:

What is the current behavior?

On iOS

1. changing between two selects can lead to a situation where the floating label for both selects is colored due to both md-input-containers of the selects having class="md-input-focused" which should not happen.
2. with a md-select open, clicking on an input in a md-input-container causes the input to get focused (floating label and ink) but then the focus gets stolen back by the md-select's md-input-container. This results in a really unintuitive and janky experience.

Issue Number:
Fixes #11345

What is the new behavior?

• fixed situations where tapping between select's in md-input-containers can leave multiple class="md-input-focused" active.
• fix focus jumping back to md-select after tapping another input.

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

Previously, tapping out of the md-select's panel would pull the focus back to the md-select's md-input-container. Now, if you tap on an element outside of the md-select's panel, the md-select stays blurred (it gets blurred when the panel opens). If you select an option, the focus returns to the md-select when the panel closes (both when using the mouse and keyboard).

This seems like a more intuitive and correct behavior since md-select panels don't have backdrops, but it does change the behavior on iOS from what it was (which was pretty bad).