feat: Support for tracing ID headers

[Anush008]

Built on top of #114

using (RequestHeaders.Use("x-request-id", "abc-123"))
    await client.ListCollectionsAsync();

using (RequestHeaders.Use("x-request-id", "abc-123")) // <- A dictionary is accepted as well.
{
    await client.UpsertAsync(...);
    await client.QueryAsync(...);
    // both carry x-request-id
}