Consider splitting Redis connection factory and `RedisTemplate` related configs

[vpavic]

Currently the entire Redis auto-configuration is conditional on presence of Jedis. If one uses Lettuce and provides LettuceConnectionFactory bean it would be nice if Boot would configure RedisTemplate and StringRedisTemplate just like it does with Jedis.

I'm aware of Lettuce first-class support proposed in #5311 is scheduled for Boot 2.0 however the situation described above would benefit Boot 1.x users as well.

Thoughts? I understand this is not a trivial change however if you'd consider it acceptable for 1.5 I'd put together a PR.

[philwebb]

My gut instinct is that this would be quite a large change to sneak into 1.5.x. I'd be interested in what others think, but my initial feeling is that we should leave 1.5.x as it is and instead focus on splitting things up for 2.0.0.

[snicoll]

I agree. We do have plans to support Lettuce so that would be a change we'll have to make anyway.

[philwebb]

Having discussed this a bit we feel like the change will be too large for the maintenance release. We'll take this on in 2.0 as part of #5311.

[vpavic]

This was resolved via #5311. I guess that means the milestone should be adjusted to 2.0.0.M1.