Fix search pos on file with leading whitespace

The extension property EditText.value trims leading/trailing
whitespace, so using it to calculate the locations of the search
matches produces incorrect indices if the file has leading whitespace.

(This affects the cursor position when going to the next/prev match.
It does not affect the highlighting of matches.)

Author: tom93

app/src/main/kotlin/org/fossify/filemanager/activities/ReadTextActivity.kt

@@ -316,7 +316,7 @@ class ReadTextActivity : SimpleActivity() {
         binding.readTextView.text?.clearBackgroundSpans()
 
         if (text.isNotBlank() && text.length > 1) {
-            searchMatches = binding.readTextView.value.searchMatches(text)
+            searchMatches = binding.readTextView.text.toString().searchMatches(text)
             binding.readTextView.highlightText(text, getProperPrimaryColor())
         }