EXPERIMENTAL: Add views to table listing

[mathemancer]

Related to #4926 #4824 #4235

This adds materialized and non-materialized views to table listing functionality in Mathesar. This means that views show up in the schema page (as tables, since the FE has no way to differentiate)

Technical details

This PR is just an experiment to see what our current behavior is when views are returned by the API along with tables. This is also related to our public "Insider Trading" dataset initiative, since we could, given read-only views, improve performance by using them instead of explorations on that (extremely large) dataset.

I'll use this PR to record notes about the behavior.

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[mathemancer]

First of all, there's no indication anywhere that a view is a view rather than a table (other than in error messages).

Schema page

• View shown as table
• Description displayed correctly
• "Find a record" button shows normal response for "table" without pkey:
  
• Renaming the "table" doesn't work (why??)
• Permissions management: TODO

Table Page

• filters, sorting, grouping: Working as normal.

Inspector: Table

• "Table" renaming: Working as normal.
• Reading description: Working
• Setting description: Not working, no error shown.
• Permissions management TODO
• Create relationship, which should make a column in the view: Not working (can't work; you can't add an fkey column to a view). Reasonable error:
  
• Create relationship, with an fkey referencing the view. Not possible, reasonable error message:
  
• Create many-to-many relationship, not possible, reasonable error:
  
• Data Explorer working fine.
• Record Summaries shows reasonable message:
  
• Import is disabled (good)
• Export works normally
• Deleting fails, reasonable message:
  

Inspector: Column

• Renaming: working as normal
• Reading/Setting description: working as normal.