chore(operators)!: remove ArithmeticOperator.FromSymbol

[pdevito3]

For later consideration in a major version. Do not merge now. #122 added FromSymbol back as [Obsolete] to keep v1.x non-breaking. Then #134 removed the Obsolete mark. This PR removes the method.

Summary

 public abstract class ArithmeticOperator
 {
     public static ArithmeticOperator Add => new AddOperator();
     ...
     public static ArithmeticOperator Modulo => new ModuloOperator();
-
-    public static ArithmeticOperator? FromSymbol(string symbol) => symbol switch { ... };
 }

• v1.14.2: ArithmeticOperator.FromSymbol(string) returns the operator for +, -, *, /, or %.
• New: The method does not exist.
• Why: No code in QueryKit calls FromSymbol, and the parser does not use it to read arithmetic. The method is dead public API. This major version removes it.

Evidence

var op = ArithmeticOperator.FromSymbol("+");

• v1.14.2: returns an AddOperator. On main it also compiles, with no warning.
• This PR:
  • Source break: error CS0117: 'ArithmeticOperator' does not contain a definition for 'FromSymbol'.
  • Binary break: System.MissingMethodException: Method not found: 'QueryKit.Operators.ArithmeticOperator QueryKit.Operators.ArithmeticOperator.FromSymbol(System.String)'.

ArithmeticOperatorTests.cs replaces the restore tests with one test:

from_symbol_is_not_part_of_the_public_api
  typeof(ArithmeticOperator).GetMethod("FromSymbol") -> null

dotnet test on the branch after the rebase on main: 465 unit tests and 297 integration tests pass, 0 failures.

Alternative to PR 148

This PR and #148 are alternatives. Merge only one of them. This PR removes FromSymbol. PR 148 keeps FromSymbol and marks it [Obsolete]. The captain picks one.

Merge Danger

Door: two-way

A later release can add the method back with the same signature.

Blast Radius: consumers

Only consumer code that calls FromSymbol breaks. Callers can use Add, Subtract, Multiply, Divide, or Modulo directly. Filter parsing does not change.