Add configurable API key support for Rule34Ripper #2145

[apoorvdarshan]

Summary

• Rule34.xxx now requires api_key and user_id for DAPI access (#2145)
• Reads credentials from config (rule34.api_key, rule34.user_id) and appends them as query parameters to API requests
• Warns users with actionable setup instructions when credentials are missing (links to https://rule34.xxx/index.php?page=account&s=options)
• Follows existing patterns (E621Ripper's loadConfig() / sendUpdate approach)

Test plan

• Added testGetAPIUrlWithCredentials — verifies credentials appear in constructed API URL
• Added testGetAPIUrlWithoutCredentials — verifies no credentials leak when unconfigured
• Renamed misnamed testShesFreakyRip → testRule34Rip
• Manual test: set rule34.api_key and rule34.user_id in rip.properties and rip a Rule34 tag URL

Closes #2145

[apoorvdarshan]

Addressed both review comments:

1. Extracted DOMAIN and API_BASE_URL constants — used across canRip(), getGID(), getDomain(), getAPIUrl(), and loadConfig().
2. getAPIUrl() now throws MalformedURLException when credentials are missing, with an actionable error message pointing to the settings page. Updated the test to assert the exception.