refactor: Cleanup Neo.grid.Body and optimize Row/Body responsibilities (#8964)

The current Neo.grid.Body implementation retains several methods and imports that are either obsolete (due to the Neo.grid.Row refactoring) or misplaced (logic that belongs in Neo.grid.Row).

Goal: Clean up and optimize Neo.grid.Body and Neo.grid.Row by removing dead code and enforcing stricter separation of concerns.

Scope:

1. Remove Unused Imports:
   • Neo.grid.Body: Remove NeoArray import (check usage).
2. Move/Refactor ID Generation:
   • getCellId: Currently in Body, called by Row. Should this move to Row? A cell ID is intrinsically tied to the Row and Column. If Row generates its own VDOM, it should probably generate its own cell IDs.
   • getRowId: Body needs this for pooling (createRowPool) and finding rows (getRowId(rowIndex)). This likely needs to stay in Body or be a static helper, as Body manages the pool.
3. Move/Refactor Styling:
   • getRowClass: Currently in Body, called by Row. Row should probably own its own class logic, or Body passes configuration.
4. Review other legacy methods:
   • Check for other methods in Body that were used by the old createRow implementation but are now unused.

Specific Tasks:

1. Analyze src/grid/Body.mjs: Identify unused imports and methods.
2. Analyze src/grid/Row.mjs: Identify dependencies on Body that should be internal.
3. Refactor: Move getCellId logic to Row.mjs (as getCellId(column))? Or keep it central? Central ensures consistency for external lookups (e.g. SelectionModel).
   • Decision: GridBody needs to lookup cells/rows for selection and navigation. So getCellId(rowIndex, dataField) MUST exist on Body (or be easily deriving). If we move it to Row, Body can't easily calculating ID without finding the Row instance first.
   • Refinement: Keep getCellId on Body for global access, but ensure Row uses it efficiently.
4. Cleanup: Remove NeoArray if unused. Remove getRowClass from Body and implement baseCls / cls logic in Row? Row already has rowCls logic. GridBody.getRowClass was an override point. If we remove it, we break extensibility? We should check if Row calls gridBody.getRowClass.

Let's start by analyzing the files.