JS: Add textbox module (#3597)

* JS: Add textbox module
* Using view_holder instead of view_dispatcher, more checks in js_textbox_show
* API version sync
* Rename emptyText() to clearText()
* Keeping view_holder allocated for thread sefety
* Js: proper comparision with 0 in js_math_sign
* Js: add comments and fix condition race in textbox

Co-authored-by: あく <alleteam@gmail.com>
Co-authored-by: nminaylov <nm29719@gmail.com>

applications/system/js_app/examples/apps/Scripts/textbox.js

@@ -0,0 +1,30 @@
+let textbox = require("textbox");
+
+// You should set config before adding text
+// Focus (start / end), Font (text / hex)
+textbox.setConfig("end", "text");
+
+// Can make sure it's cleared before showing, in case of reusing in same script
+// (Closing textbox already clears the text, but maybe you added more in a loop for example)
+textbox.clearText();
+
+// Add default text
+textbox.addText("Example dynamic updating textbox\n");
+
+// Non-blocking, can keep updating text after, can close in JS or in GUI
+textbox.show();
+
+let i = 0;
+while (textbox.isOpen() && i < 20) {
+    print("console", i++);
+
+    // Add text to textbox buffer
+    textbox.addText("textbox " + to_string(i) + "\n");
+
+    delay(500);
+}
+
+// If not closed by user (instead i < 20 is false above), close forcefully
+if (textbox.isOpen()) {
+    textbox.close();
+}