Add BC performance knowledge from OptimAL learnings

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

microsoft/knowledge/performance/avoid-repeating-unchanged-validation.good.al

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+// Quantity validation depends only on Quantity and Unit Price in this demo.
+table 50371 "Perf Validated Line"
+{
+    DataClassification = CustomerContent;
+
+    fields
+    {
+        field(1; "Line No."; Integer) { }
+        field(2; Quantity; Decimal)
+        {
+            trigger OnValidate()
+            begin
+                Amount := Quantity * "Unit Price";
+            end;
+        }
+        field(3; "Unit Price"; Decimal) { }
+        field(4; Amount; Decimal) { }
+        field(5; Note; Text[100]) { }
+    }
+
+    keys
+    {
+        key(PK; "Line No.") { Clustered = true; }
+    }
+}
+
+codeunit 50372 "Perf Validation Good"
+{
+    procedure UpdateLine(LineNo: Integer; NewQuantity: Decimal; NewNote: Text[100])
+    var
+        Line: Record "Perf Validated Line";
+    begin
+        Line.Get(LineNo);
+        Line.Validate(Quantity, NewQuantity);
+        Line.Note := NewNote;
+        Line.Modify(false);
+    end;
+}