Do not raise error for search archive results

Start in lib/serpapi/client.rb, especially the get handling around lines 154 and 236. Trace how archive search responses with HTTP 200 and a top-level "error" key are processed, then verify that failed searches can be retrieved without raising an error condition.

If the HTTP response code is 200, we should not raise an error condition. In practice, trying to investigate a set of failed searches is impossible with the client as it currently works. Consider the following:

Processing IDs from failed-searches.txt...
--------------------------------------------------------------------------------
Search ID                      | Created At                | Processed At              | Time Taken
--------------------------------------------------------------------------------
6935c0b9a0cb1015d74ef919: Error - HTTP request failed with status: 200 OK error: Google hasn't returned any results for this query. from url: https://serpapi.com/searches/6935c0b9a0cb1015d74ef919.json
6935c10c6372f3288d198835: Error - HTTP request failed with status: 200 OK error: Google hasn't returned any results for this query. from url: https://serpapi.com/searches/6935c10c6372f3288d198835.json
6935c140d1a72b12298a4c3a: Error - HTTP request failed with status: 200 OK error: Google hasn't returned any results for this query. from url: https://serpapi.com/searches/6935c140d1a72b12298a4c3a.json
6935c1847dcfbe884d95f202: Error - HTTP request failed with status: 200 OK error: Google hasn't returned any results for this query. from url: https://serpapi.com/searches/6935c1847dcfbe884d95f202.json
6935c23c0fa72e068915493a: Error - HTTP request failed with status: 200 OK error: Google hasn't returned any results for this query. from url: https://serpapi.com/searches/6935c23c0fa72e068915493a.json
6935c26f80c963a0739496b7: Error - HTTP request failed with status: 200 OK error: Google hasn't returned any results for this query. from url: https://serpapi.com/searches/6935c26f80c963a0739496b7.json
6935c2a2d99612e9a0b828b2: Error - HTTP request failed with status: 200 OK error: Google hasn't returned any results for this query. from url: https://serpapi.com/searches/6935c2a2d99612e9a0b828b2.json

The search exists, the response was successful, but because of the search api using the same get machinery:

https://github.com/serpapi/serpapi-ruby/blob/024b9ebe3320704a117d46043a49238c8dc14ddc/lib/serpapi/client.rb#L154

It uses the same handling of the presence of a top level "error" key:

https://github.com/serpapi/serpapi-ruby/blob/024b9ebe3320704a117d46043a49238c8dc14ddc/lib/serpapi/client.rb#L236

Instead, we should allow retrieval of failed searches from the archive without raising an error.