gRPC Swift 1.17.0

SemVer Minor

• Allow server handlers to send response headers directly by manually accepting an RPC (#1599)
• Improve Sendable checking for server handlers (#1605)

SemVer Patch

• Emit 'swift-format-ignore-file' in generated files to avoid having them reformatted by swift-format (#1606, patch credit to @smikhanov)
• Fix warnings from nightly Swift builds (#1600)
• Fix stream accounting bug when stream close leads to connection close (#1603)
• Improve cancellation support for async calls (#1608)
• Handle non-200 status codes more gracefully (#1613)
• Bump version number to 1.17.0 (#1614)

Other Changes

• Allow network framework tests to be skipped when no user interaction (#1602)
• Update allocation counts (#1609)