API - Add upgrade-safe checks to ensure table exists before reading

[colemanw]

Overview

This adds efficient checks into the api (v3 and v4) to ensure a DAO table exists before trying to read from it.
This prevents hard-crashes in the UI when there are pending updates (or during the upgrade process itself)

Before

Checks on fields but not the entire table.

After

Efficiently check if a table exists (without requiring an extra query) before trying to read from it.

Technical Details

Adds information to each DAO file about what extension it belongs to (const EXT is either 'civicrm' or the name of the extension). Avoids doing version checks on non-core tables as extension checks would have to be implemented differently (a good idea but not part of this PR).

Comments

TODO: Add these checks for extensions' tables if there are pending extension upgrades.
Another TODO would be to also perform this check before attempting a join. Currently this check is limited to the primary table.

[civibot]

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[seamuslee001]

Test fails look related @colemanw and also needs a rebase

[colemanw]

@seamuslee001 I rebased & fixed the test issue

[seamuslee001]

This looks good to me merging