v9.0.0-alpha.5

Changes from 9.0.0-alpha.4:

Serverless client merged back in

The @elastic/elasticsearch-serverless client is being deprecated, and its functionality has been merged back into this client. This should have zero impact on the way the client works, except that a new serverMode option has been added. When it's explicitly set to "serverless" by a user, a few default settings and behaviors are changed:

• turns off sniffing and ignores any sniffing-related options
• ignores all nodes passed in config except the first one, and ignores any node filtering and selecting options
• enables compression and TLSv1_2_method (same as when configured for Elastic Cloud)
• adds an elastic-api-version HTTP header to all requests
• uses CloudConnectionPool by default instead of WeightedConnectionPool
• turns off vendored content-type and accept headers in favor or standard MIME types

Docstrings for types that differ between stack and serverless have also been updated to indicate when that is the case.