[TextInputLayout] Focused underline stroke can't be hidden in filled mode

@afohrman is already working on this.

Since Nov 10, 2022.

**Description:**

TextInputLayout focused underline stroke can't be hidden in filled mode (`app:boxBackgroundMode="filled"`).

Our application design requires a filled mode TextInputLayout that has a stroke in unfocused state, and does not have a stroke in focused state. This was possible to achieve in Material Components version 1.3, but not in later versions (tested with 1.6 and 1.7).

**Expected behavior:**

Both of these approaches should hide the underline stroke in focused state:

1. `boxStrokeWidthFocused` is set to `0dp` (this solution used to work in version 1.3)

2. `boxStrokeColor` color state list entry for `state_focused` is set to transparent

**Source code:**
1. boxSrokeWidthFocused is ignored in filled mode, as separate drawables are now used instead: https://github.com/material-components/material-components-android/blob/release-1.7/lib/java/com/google/android/material/textfield/TextInputLayout.java#L4087

2. Default underline drawable is always drawn, and focused underline is drawn on top. Meaning that transparent boxStrokeColor shows the underlaying defaultStrokeColor instead: https://github.com/material-components/material-components-android/blob/release-1.7/lib/java/com/google/android/material/textfield/TextInputLayout.java#L2817

**Minimal sample app repro:** Please let me know if a sample would be useful.

**Android API version:** Any API version

**Material Library version:** 1.6, 1.7

**Device:** Any device