[MCP] Toggle Default via field on MCP Configuration pages

[onbuyuka]

Summary

Replaces the Set as Default / Clear Default actions on the MCP Configuration Card and List pages with an editable Default field. The new field's OnValidate trigger toggles the designation directly via the existing MCPConfigImplementation.SetAsDefaultConfiguration / ClearDefaultConfiguration helpers, so behaviour is unchanged - just exposed through the field instead of two separate actions.

Changes

• MCP Config Card (page 8351): made Default field editable when the row is not the built-in default; added OnValidate trigger; removed SetAsDefault and ClearDefault actions and their promoted refs.
• MCP Config List (page 8350): removed SetAsDefault and ClearDefault repeater actions and their promoted refs (the column's Default field already toggles the designation now).

Fixes AB#612699

[github-actions]

$\textbf{🟡\ Medium\ Severity\ —\ Security} \quad \color{gray}{\texttt{\small Iteration\ 1}}$

Missing AccessByPermission on Default field

The removed SetAsDefault and ClearDefault actions both declared AccessByPermission = tabledata "MCP Configuration" = M, providing an explicit UI-level permission guard. The new Default field's OnValidate trigger has no equivalent AccessByPermission property, so the UI-level guard is silently dropped.

Recommendation:

• Add AccessByPermission = tabledata "MCP Configuration" = M to the Default field definition to preserve the same access control that the replaced actions enforced.

field(Default; Rec.Default)
{
    Caption = 'Default';
    ToolTip = '...';
    Editable = not IsDefault;
    AccessByPermission = tabledata "MCP Configuration" = M;

    trigger OnValidate()
    begin
        ...
    end;
}

Line mapping was unavailable, so this was posted as an issue comment.

_{👍 useful · ❤️ especially valuable · 👎 wrong - reply with why}