Add .aiexclude file for safer Gemini usage

[thomashorta]

Gemini is now embedded in Android Studio but it shares data with Google to provide code assistance, therefore we should include an .aiexclude file (similar to .gitignore) to avoid sensitive data being shared (like keys).

This PR adds an initial .aiexclude file containing such files.

Based on:
https://developer.android.com/studio/preview/gemini/aiexclude

[dangermattic]

	1 Warning
⚠️	PR is not assigned to a milestone.

Generated by 🚫 Danger

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarCloud

[wpmobilebot]

📲 You can test the changes from this Pull Request in WordPress by scanning the QR code below to install the corresponding build.

	App Name	WordPress
	Flavor	Jalapeno
	Build Type	Debug
	Version	pr20827-03fc44b
	Commit	03fc44b
	Direct Download	wordpress-prototype-build-pr20827-03fc44b.apk

Note: Google Login is not supported on these builds.

[wpmobilebot]

📲 You can test the changes from this Pull Request in Jetpack by scanning the QR code below to install the corresponding build.

	App Name	Jetpack
	Flavor	Jalapeno
	Build Type	Debug
	Version	pr20827-03fc44b
	Commit	03fc44b
	Direct Download	jetpack-prototype-build-pr20827-03fc44b.apk

Note: Google Login is not supported on these builds.

[wzieba]

This looks good. Excluded files contain all secret files declared in .configure as well as all build directories that could contain these secrets. Thank you @thomashorta !