[FEA][DynamicEmb] Auto selective prefetch & caching size

[JacoCheung]

There are 2 bugs regarding the prefetch/caching

1. Currently, the dynamceb_prefetch() will loop on all tables, and will fail if any table is not caching.
   Therefore when there are multiple dynamicemb tables that comprise both caching and non-caching table. The prefetch will not work. We need to fix this. Another issue is the caching flag always set by the first table. Is this expected?

2. The caching bucket capacity is fixed to 1024. If the table has smaller than 1024 , it reports error (assert failure) and exits. A better way is to report a warning and allocate a 1024 bucket.

[shijieliu]

1. we will seperate hbm lookup module with hbm + dram lookup module
2. do alignment for capacity