Stop constraining grid cell editors to the viewport (#317)

## Rationale

Tabbing past the right edge of the window in a wide EHR data-entry grid
draws the cell editor over the wrong column and never scrolls the page,
so the user types into a box that appears to belong to one column while
the value goes to another. The LDK cell-editing plugin aligned editors
with a trailing `?`, which tells Ext to clamp the editor inside the
browser viewport; EHR grids grow to fit their columns and rely on the
page to scroll, so the clamp pinned off-screen editors to the window
edge and left the browser nothing to scroll to. With the constraint
removed the editor sits on its cell and focusing it scrolls the page, so
tabbing beyond the width of the screen now scrolls horizontally to
follow the active cell.

## Related Pull Requests

None.

## Changes

- Drop the viewport constraint from the cell editor alignment in the LDK
cell-editing plugin, so editors always align to their cell and the page
scrolls to keep the active editor visible.

Author: labkey-martyp

LDK/resources/web/LDK/plugin/CellEditing.js

@@ -53,7 +53,8 @@ Ext4.define('LDK.grid.plugin.CellEditing', {
             hasCellEditOverrides: true,
             revertInvalid: false,
             completeOnEnter: false,
-            alignment: 'tl-tl?'
+            // No trailing '?': viewport-constraining pins editors for off-screen columns to the window edge instead of their cell
+            alignment: 'tl-tl'
         });
 
         //NOTE: this is an override to fix an Ext4 bug involving revertInvalid