Terminal: Convert main_split_config.xml into Kotlin

Construct rules as a Kotlin code instead of a static XML so it's
now much easier to modify the behaviors programatically.

In addition, fix the definition of 'activity_split_ratio' in xml.
It was defined as a "dimension" but it should be a float value.

Bug: 404452165
Test: Check the settings UI and see no differences
Change-Id: Ieb8a961ea3f9190798a37d4b0b02c27752fdaa94
diff --git a/android/TerminalApp/res/values/config.xml b/android/TerminalApp/res/values/config.xml
index 7f0b5e6..a2c9183 100644
--- a/android/TerminalApp/res/values/config.xml
+++ b/android/TerminalApp/res/values/config.xml
@@ -16,4 +16,5 @@
 
 <resources xmlns:xliff="urn:oasis:names:tc:xliff:document:1.2">
     <bool name="terminal_portrait_only">true</bool>
+    <item name="activity_split_ratio" format="float" type="dimen">0.3</item>
 </resources>
diff --git a/android/TerminalApp/res/values/dimens.xml b/android/TerminalApp/res/values/dimens.xml
deleted file mode 100644
index e00ef7c..0000000
--- a/android/TerminalApp/res/values/dimens.xml
+++ /dev/null
@@ -1,19 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!--  Copyright 2024 The Android Open Source Project
-
-     Licensed under the Apache License, Version 2.0 (the "License");
-     you may not use this file except in compliance with the License.
-     You may obtain a copy of the License at
-
-          http://www.apache.org/licenses/LICENSE-2.0
-
-     Unless required by applicable law or agreed to in writing, software
-     distributed under the License is distributed on an "AS IS" BASIS,
-     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-     See the License for the specific language governing permissions and
-     limitations under the License.
- -->
-
-<resources>
-    <dimen name="activity_split_ratio">0.3</dimen>
-</resources>
\ No newline at end of file