Default request timeouts

[rcoh]

• Rename API timeouts to operation timeouts and move them into TimeoutConfig
• Remove currently unused TCP/HTTP timeout config structs
• Add connect_timeout to TimeoutConfig and default it to 3100 milliseconds
• Implement support for connect timeout
• Integration test all supported timeouts

[jdisanti]

Breaking out the per-operation override capability out into #1732 since that requires a good bit of design work and refactoring.

[jdisanti]

Defaults should be the following for now:

connectTimeoutInMillis: 3100
tlsNegotiationTimeoutInMillis: 3100

Taken from the current sdk-default-configuration.json standard mode: https://github.com/awslabs/aws-sdk-rust/blob/a58ba1a21f383b26e09ebdd4cc07d57a87e30388/aws-models/sdk-default-configuration.json#L12-L16

[jdisanti]

It looks like only the API timeouts have been implemented, so these defaults can't be set yet. Will need to implement the TCP and HTTP timeouts.

Edit: From discussion with @Velfi, these timeouts don't need to get implemented. I will pare down the configuration interface to remove them for now, and will update this issue description with remaining work.