Make it possible to set the connectionRequestTimeout in httpcomponents-httpclient

In a scenario where you have multiple connection pools, and one of them has no available connections, you will still have a lot of incoming requests waiting patiently in line for an available connection in the drained pool. If you have enough traffic this will bring down your application even though only parts of it were expected to suffer.

I tried finding the same setting for the other resolvers, but afaik only httpcomponents-httpclient has this setting.

See also: https://jira.spring.io/browse/SPR-12166