[TextInputLayout] Setting end icon gravity

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**Is your feature request related to a problem? Please describe.**

In a multi line TextInputEditText the end icon is always centered, but in some cases we need it to be set to top or at the bottom of the layout.

After some internet research I didn't find any suitable solution. I tried to explore the implementation class TextInputLayout.java and found out that the end icon is place as a drawable in CheckableImageButton (com.google.android.material.R.id.text_input_end_icon) and the button is place in a FrameLayout.

What I did is finding the button by its ID and then customize the layout params.

```java
// using viewbinding
private ActivityCommentBinding mBinding;

// change the end icon gravity
FrameLayout.LayoutParams params = (FrameLayout.LayoutParams) mBinding.commentTextLayout
.findViewById(com.google.android.material.R.id.text_input_end_icon)
.getLayoutParams();
params.gravity = Gravity.TOP;
mBinding.commentTextLayout
.findViewById(com.google.android.material.R.id.text_input_end_icon)
.setLayoutParams(params);

```
Result:


**Describe the solution you'd like**
I think it would be useful to have a TextInputLayout XML attribute to set the end icon gravity.

Start by reading TextInputLayout.java and the CheckableImageButton identified in the issue to understand how the end icon is positioned. Define the public XML attribute and its supported gravity values, then verify that multiline end icons can be aligned at the top or bottom while preserving existing behavior.

Written by the indexing model from the issue text.