Updated all references from the previous default SERP provider to SerpApi, including API keys, proxy configuration, and documentation links. Adjusted aviation.js to use SerpApi endpoints and parameters, and updated testloader.js to reflect the new provider. This change standardizes the search engine scraping integration to use SerpApi.
1. Separated the data listing available HTTP proxy services into a separate file. (data/available_proxies.json)
2. Excluded the architecture of the user's PC (e.g., 32-bit, 64-bit) from the User-Agent in HTTP requests.
