[Autofill] Increase touch target of text fields in the CVC unmask dialog

Before this patch, the expiration month, year, and CVC text fields in
the CVC unmask dialog were all 45dp tall, which is smaller than the 48dp
required for accessibility.

This patch sets the minimum height to 48dp for the expiration month,
year, and CVC text fields.

After this patch,the expiration month, year, and CVC text fields are at
least 48dp tall.

Bug: 977272
Change-Id: I955bc9a4ca88e4d813119d7e1f3f1f697a27aafe
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2585689Reviewed-by: David Trainor <dtrainor@chromium.org>
Commit-Queue: Rouslan Solomakhin <rouslan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#836368}

chrome/android/java/res/layout/autofill_card_unmask_prompt.xml

@@ -75,6 +75,7 @@
                   android:layout_width="wrap_content"
                   android:layout_height="wrap_content"
                   android:layout_marginStart="16dp"
+                  android:minHeight="48dp"
                   android:width="50sp"
                   android:maxLength="2"
                   android:gravity="center_horizontal"
@@ -93,6 +94,7 @@
                   android:id="@+id/expiration_year"
                   android:layout_width="wrap_content"
                   android:layout_height="wrap_content"
+                  android:minHeight="48dp"
                   android:width="50sp"
                   android:maxLength="2"
                   android:gravity="center_horizontal"
@@ -109,6 +111,7 @@
                 android:layout_height="wrap_content"
                 android:layout_width="wrap_content"
                 android:layout_marginStart="16dp"
+                android:minHeight="48dp"
                 android:ems="5"
                 android:imeOptions="actionDone"
                 android:imeActionLabel="@string/autofill_save_card_prompt_confirm"