Mock promptWindowsSpeedUpSites handler in onboarding unit tests

[fluiddot]

Related to #211 as it when the handler was introduced.

Proposed Changes

• Mock promptWindowsSpeedUpSites IPC handled to avoid test failures.

Testing Instructions

• Observe that all CI jobs succeed.

Pre-merge Checklist

• Have you checked for TypeScript, React or other console errors?

[dcalhoun]

I note we have one other error logged in the test results, but it appears unrelated to the target of the proposed changes.

Test log error

    console.warn
      PHP.run() output was: #!/usr/bin/env php


      at _NodePHP.run (node_modules/@php-wasm/node/index.cjs:72997:17)

    console.error
      PHPExecutionFailureError2: PHP.run() failed with exit code 1 and the following output:
          at _NodePHP.run (/Users/davidcalhoun/Sites/a8c/studio/node_modules/@php-wasm/node/index.cjs:72998:23) {
        response: _PHPResponse {
          httpStatusCode: 500,
          headers: { 'x-powered-by': [Array], 'content-type': [Array] },
          bytes: Uint8Array(19) [
             35,  33,  47, 117, 115, 114,
             47,  98, 105, 110,  47, 101,
            110, 118,  32, 112, 104, 112,
             10
          ],
          exitCode: 1,
          errors: ''
        },
        source: 'request'
      }

      at _NodePHP.run (node_modules/@php-wasm/node/index.cjs:73003:17)

[fluiddot]

I note we have one other error logged in the test results, but it appears unrelated to the target of the proposed changes.

Yep, I checked the output of recent trunk commits, and seems the error log was introduced in #203. cc @katinthehatsite