Combine ReactJSXElementValidator with main module (#28317)

There are too many layers to the JSX runtime implementation. I think
basically everything should be implemented in a single file, so that's
what I'm going to do.

As a first step, this deletes ReactJSXElementValidator and moves all the
code into ReactJSXElement. I can already see how this will help us
remove more indirections in the future.

Next I'm going to do start moving the `createElement` runtime into this
module as well, since there's a lot of duplicated code.

DiffTrain build for commit ec160f3.

compiled-rn/facebook-fbsource/xplat/js/RKJSModules/vendor/react-test-renderer/cjs/ReactTestRenderer-dev.js

@@ -25686,7 +25686,7 @@ if (__DEV__) {
       return root;
     }
 
-    var ReactVersion = "18.3.0-canary-c82009771-20240219";
+    var ReactVersion = "18.3.0-canary-ec160f32c-20240219";
 
     // Might add PROFILE later.
 

compiled-rn/facebook-fbsource/xplat/js/RKJSModules/vendor/react-test-renderer/cjs/ReactTestRenderer-prod.js

@@ -9176,7 +9176,7 @@ var devToolsConfig$jscomp$inline_1014 = {
     throw Error("TestRenderer does not support findFiberByHostInstance()");
   },
   bundleType: 0,
-  version: "18.3.0-canary-c82009771-20240219",
+  version: "18.3.0-canary-ec160f32c-20240219",
   rendererPackageName: "react-test-renderer"
 };
 var internals$jscomp$inline_1195 = {
@@ -9207,7 +9207,7 @@ var internals$jscomp$inline_1195 = {
   scheduleRoot: null,
   setRefreshHandler: null,
   getCurrentFiber: null,
-  reconcilerVersion: "18.3.0-canary-c82009771-20240219"
+  reconcilerVersion: "18.3.0-canary-ec160f32c-20240219"
 };
 if ("undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__) {
   var hook$jscomp$inline_1196 = __REACT_DEVTOOLS_GLOBAL_HOOK__;

compiled-rn/facebook-fbsource/xplat/js/RKJSModules/vendor/react-test-renderer/cjs/ReactTestRenderer-profiling.js

@@ -9604,7 +9604,7 @@ var devToolsConfig$jscomp$inline_1056 = {
     throw Error("TestRenderer does not support findFiberByHostInstance()");
   },
   bundleType: 0,
-  version: "18.3.0-canary-c82009771-20240219",
+  version: "18.3.0-canary-ec160f32c-20240219",
   rendererPackageName: "react-test-renderer"
 };
 var internals$jscomp$inline_1236 = {
@@ -9635,7 +9635,7 @@ var internals$jscomp$inline_1236 = {
   scheduleRoot: null,
   setRefreshHandler: null,
   getCurrentFiber: null,
-  reconcilerVersion: "18.3.0-canary-c82009771-20240219"
+  reconcilerVersion: "18.3.0-canary-ec160f32c-20240219"
 };
 if ("undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__) {
   var hook$jscomp$inline_1237 = __REACT_DEVTOOLS_GLOBAL_HOOK__;