Distinguish error fixtures for invalid code

Renames some error fixtures for clarity, "error.invalid-*" are fixtures that are 
expected to fail for invalid input, where other "error.*" fixtures are basically 
todos. While i was here i clarified the error messages for invalid useMemo 
callbacks, and changes the error severity from Invariant to InvalidInput.

compiler/forget/src/Inference/InlineUseMemo.ts

@@ -100,15 +100,15 @@ export function inlineUseMemo(fn: HIRFunction): void {
             }
 
             if (body.loweredFunc.params.length > 0) {
-              CompilerError.invariant(
-                "Did not expect any arguments to useMemo callback",
+              CompilerError.invalidInput(
+                "useMemo callbacks may not accept any arguments",
                 body.loc
               );
             }
 
             if (body.loweredFunc.async || body.loweredFunc.generator) {
-              CompilerError.invariant(
-                "Did not expect useMemo callback to be async or a generator",
+              CompilerError.invalidInput(
+                "useMemo callbacks may not be async or generator functions",
                 body.loc
               );
             }

compiler/forget/src/__tests__/fixtures/compiler/error.invalid-useMemo-async-callback.expect.md

@@ -15,7 +15,7 @@ function component(a, b) {
 ## Error
 
 ```
-[ReactForget] Invariant: Did not expect useMemo callback to be async or a generator (2:4)
+[ReactForget] InvalidInput: useMemo callbacks may not be async or generator functions (2:4)
 ```
           
       

compiler/forget/src/__tests__/fixtures/compiler/error.invalid-useMemo-callback-args.expect.md

@@ -13,7 +13,7 @@ function component(a, b) {
 ## Error
 
 ```
-[ReactForget] Invariant: Did not expect any arguments to useMemo callback (2:2)
+[ReactForget] InvalidInput: useMemo callbacks may not accept any arguments (2:2)
 ```