Get bunx tests to pass on Windows

[Jarred-Sumner]

What does this PR do?

• Fixes "unable to find executable" error caused by checking the last write time of <bunx-dir>/node_modules/uglifyjs/package.json rather than <bunx-dir>/package.json
• should fix SharingViolation error
• Should fix flakiness from deleting tmp dirs, I think

How did you verify your code works?

Tests

[github-actions]

❌ @Jarred-Sumner 2 files with test failures on bun-darwin-aarch64:

• test/js/bun/http/serve.test.ts 8 failing
• test/js/bun/spawn/spawn-kill-signal.test.ts 1 failing

View test output

^{#d82997124ee2b50bbd24d13a873793587363e311}

[github-actions]

❌ @Jarred-Sumner 3 files with test failures on linux-x64:

• test/integration/next-pages/test/dev-server.test.ts 1 failing
• test/integration/next-pages/test/next-build.test.ts 1 failing
• test/js/node/watch/fs.watchFile.test.ts 1 failing

View test output

^{#d82997124ee2b50bbd24d13a873793587363e311}

[github-actions]

❌ @Jarred-Sumner 2 files with test failures on linux-x64-baseline:

• test/integration/next-pages/test/dev-server.test.ts 1 failing
• test/integration/next-pages/test/next-build.test.ts 1 failing

View test output

^{#d82997124ee2b50bbd24d13a873793587363e311}

[github-actions]

❌ @Jarred-Sumner 10 files with test failures on bun-windows-x86_64-haswell

• test\cli\install\migration\complex-workspace.test.ts 21 failing
• test\cli\install\registry\bun-install-registry.test.ts 2 failing
• test\integration\esbuild\esbuild.test.ts 1 failing
• test\integration\next-pages\test\dev-server.test.ts SIGTERM
• test\integration\next-pages\test\next-build.test.ts 1 failing
• test\js\bun\glob\scan.test.ts 2 failing
• test\js\bun\shell\bunshell.test.ts 1 failing
• test\js\node\dns\node-dns.test.js SIGTERM
• test\js\third_party\esbuild\esbuild-child_process.test.ts 1 failing
• test\js\web\fetch\body-stream.test.ts STATUS_BREAKPOINT

View test output

^{#d82997124ee2b50bbd24d13a873793587363e311}

[github-actions]

❌ @Jarred-Sumner 2 files with test failures on bun-darwin-x64:

• test/js/bun/spawn/spawn.test.ts SIGTERM
• test/js/bun/test/test-test.test.ts 1 failing

View test output

^{#d82997124ee2b50bbd24d13a873793587363e311}

[paperdave]

glad to see this was found.

[jdalton]

There's is a lot changed here. Hard to reason about all of it (means I defer to unit tests and CI happiness), but would also welcome any context/note comments.