ModeShape's workspace cache should not be based on Infinispan

ModeShape's current WorkspaceCache implementation is based on Infinispan and essentially represents an in-memory, eviction supporting cache.

ModeShape 5 still requires the WorkspaceCache as is, but we need to replace Infinispan with another in memory cache that:

• is thread-safe based on the semantics of the ConcurrentMap
• supports some form of eviction to avoid overloading the memory and potentially causing OOMs

The new cache implementation should be as lightweight as possible, avoiding "heavy" 3rd party dependencies (e.g. Guava).