Feat: Add ```CREATE VIEW``` or ```CREATE MATERIALIZED VIEW```

**Is your feature request related to a problem? Please describe.**
Previous issue #223 mentioned supporting approximate aggregate in a long windows, however it is better to support something like *MATERIALIZED VIEW* to make a query to be scheduled later by job manager.

**Describe the solution you'd like**
Add support for ```CREATE VIEW``` or ```CREATE MATERIALIZED VIEW``` for storing precomputed result of a query and support to trigger it to be refreshed later upon demand.

The issue is about adding CREATE VIEW and CREATE MATERIALIZED VIEW support to OpenMLDB, a C++ database for machine learning. Look at the SQL parser and query execution engine to understand how queries are currently processed. Research how materialized views are refreshed and integrated with a job scheduler. Check existing issues like #223 for context on approximate aggregates and long windows.

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