Upgrade tsx to v4.x and use it directly to fix issue with Node v18.19

[Tobbe]

We saw some issues with our unit tests on Node v18.19. See links below more info

nodejs/node#51048
https://github.com/privatenumber/tsx/releases/tag/v4.1.2

Dom worked around this by pinning Node to 18.18. This PR un-pinns Node, to get v18.19. After clearing the GitHub cache (twice) I was able to reproduce the issue in this PR on CI. https://github.com/redwoodjs/redwood/actions/runs/7139459915/job/19446057016?pr=9653

# /home/runner/work/redwood/redwood/packages/eslint-plugin/src/__tests__/service-type-annotations.test.ts:1
# import { describe, it } from 'node:test'
# ^^^^^^
# SyntaxError: Cannot use import statement outside a module
#     at internalCompileFunction (node:internal/vm:73:18)
#     at wrapSafe (node:internal/modules/cjs/loader:1274:20)
#     at Module._compile (node:internal/modules/cjs/loader:1320:27)
#     at Module._extensions..js (node:internal/modules/cjs/loader:1414:10)
#     at Module.load (node:internal/modules/cjs/loader:1197:32)
#     at Module._load (node:internal/modules/cjs/loader:1013:12)
#     at ModuleWrap.<anonymous> (node:internal/modules/esm/translators:202:29)
#     at ModuleJob.run (node:internal/modules/esm/module_job:195:25)
#     at async ModuleLoader.import (node:internal/modules/esm/loader:336:24)
#     at async loadESM (node:internal/process/esm_loader:34:7)
# Node.js v18.19.0
# Subtest: /home/runner/work/redwood/redwood/packages/eslint-plugin/src/__tests__/service-type-annotations.test.ts
not ok 2 - /home/runner/work/redwood/redwood/packages/eslint-plugin/src/__tests__/service-type-annotations.test.ts
  ---
  duration_ms: 183.717365
  location: '/home/runner/work/redwood/redwood/packages/eslint-plugin/src/__tests__/service-type-annotations.test.ts:1:1'
  failureType: 'testCodeFailure'
  exitCode: 1
  error: 'test failed'
  code: 'ERR_TEST_FAILURE'

Then, upgrading tsx to latest version (v4.1.3) we get this error message instead

# node:internal/process/esm_loader:40
#       internalBinding('errors').triggerUncaughtException(
#                                 ^
# Error: tsx must be loaded with --import instead of --loader
# The --loader flag was deprecated in Node v20.6.0 and v18.19.0
#     at z (file:///home/runner/work/redwood/redwood/node_modules/tsx/dist/esm/index.mjs:1:1800)
#     at Hooks.addCustomLoader (node:internal/modules/esm/hooks:202:24)
#     at Hooks.register (node:internal/modules/esm/hooks:168:16)
#     at async initializeHooks (node:internal/modules/esm/utils:167:5)
#     at async customizedModuleWorker (node:internal/modules/esm/worker:104:24)
# Node.js v18.19.0
# Subtest: /home/runner/work/redwood/redwood/packages/eslint-plugin/src/__tests__/unsupported-route-components.test.ts

So, the final fix was to just use tsx directly, letting it act like a wrapper around node, instead of providing it as a loader. Which is the recommended way to use tsx anyway.
From it's README:

Usage

tsx is a Node.js wrapper

tsx wraps around Node.js to enhance it with TypeScript support. Because it's a drop-in replacement for node, it supports all Node.js command-line flags.

# --no-warnings is a Node.js flag
tsx --no-warnings ./file.ts