Rename Spring Session properties that depend on Spring Data

[wilkinsona]

Spring Session has two modules that depend on Spring Data:

• spring-session-data-mongodb
• spring-session-data-redis

Currently, Boot's properties classes and prefixes for these are named as follows:

• MongoSessionProperties (spring.session.mongodb)
• RedisSessionProperties (spring.session.redis)

This doesn't align well with the names of their modules or with other Data MongoDB and Data Redis properties.

They should become:

• SessionDataMongoProperties (spring.session.data.mongodb)
• SessionDataRedisProperties (spring.session.data.redis)