Payload for loading/caching image data

[hepengfe]

Is your feature request related to a problem? Please describe.
We plan to have a payload entry to load and cache image data, and it has the following functionalities.

1. It caches image data which are loaded or transformed
2. It can load data from data source or cache, for example, pmg image data.
3. It's associated with two entry data
   a. Meta data
   b. Loading method: user can further design this entry.
4. it has two attributes.
   a. uri: A uniform resource identifier for indexing a image's data source
   b. cache: it stores the cached data

Depends on

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Additional context

• This is part of the data efficiency project
• This PR should be made to the master branch.
• After the data tuple class is finished, we may switch to a new branch for integration.