Fixes #1407

We (mistakenly) assumed that the paragraph in the logs documentation stating Make sure to always convert 64-bit unsigned integers to strings applied to all unsigned integers, but this is only an issue for log attributes. For all other values, we can safely ingest these.

We change the jsonwriter to write the actual numerical value again, and update sentry_logs to store unsigned integers as string sentry_value_t objects.

ToDo:

• ✅ update logs code to store unsigned ints as sentry_value_t strings instead