* Move `DatabaseHelp` to `DatabaseStep`

* Remove `redux-form` usage from setup

* Fix unit tests

* Move engine state to redux

* Revert test changes

* Code style fix

* Start task scheduler at end of startup.

The sync db task does a lot of db work to be addressed in a later
commit. But it also begins firing tasks _during startup_. Lets prevent
syncs and other tasks while we are starting up until we have finished.

Scheduler can be set to standby mode while we wait on finishing up
initializing and then start after.

* docstring cleanup and comments

We are not running tests which exercise those *.stories files, hence it
is not fair to include them in the coverage analysis.

Pursuant to https://github.com/metabase/metabase/issues/22174.

Make the JSON columns work on MySQL in exactly the same way as they do in Postgres. Bit of a refactor about some bits of Postgres implementation.

Importantly, MariaDB JSON columns work significantly more like SQL Server JSON columns. That is, they aren't JSON columns at all with respect to type, they're text columns - and we don't detect them very well as JSON columns qua JSON columns. So MariaDB is not supported at this time.

* fix yarn docs issues

* fix webpack config issue

* Make persisted models use "create table as"

There are outstanding issues with database type erasure.

If we try to recreate table columns based on the saved
definition we'll get types such as `type/Structured` that
could be `json`, `xml`, etc. Perhaps worse, consider 'citext' that we
see as `type/Text`. If they have queries on the model such as
`where email = 'JOE@example.com'` that would start to return different
results if we created the table with `email text` rather than
`email citext`.

By using `create table ... as select ....`, we avoid this issue as the db types
selected will match the db types queried.

* Remove unused require

* Missed validatiy check needs a query to create table as

* separate some pure functions that live on FieldValuesWidget

* Fix some variable name weirdness

* remove memoize decorator

* remove babel plugins

* Fix AccordionList

* remove memoize from accordionlist

* fix value vs type issue with wrapped classes

* fix typechecking in memoize class

* rewrote query to export the memoized class directly

These loops could be long running, so before removing or adding a cache
we should double check that the state of the persisted info is still
valid for the job.

* Only apply persistence substitution when there's no sandboxing

* Added test for sandboxed persistence

* Recursively apply persisted-info/native queries

* Move test into permissions test that has ee code

* migrate to TypeScript, add type annotations
* include props definition
* support Storybook
* add a basic unit test

* Verify active database for `GET api/health`

Previously unconditionally responded with 200, status "ok" if we were
done initializing, even when we had 1500 stale db connections
somehow ().

Now attempt to connect to the database:

```shell
❯ http get localhost:3000/api/health -pb
{
    "status": "ok"
}

❯ http get localhost:3000/api/health
HTTP/1.1 503 Service Unavailable
...
{
    "status": "Error getting db connection"
}
```

and logging to the server
```
2022-05-10 22:05:16,911 WARN server.routes :: Error in api/health database check
java.lang.ArithmeticException: Divide by zero
	at clojure.lang.Numbers.divide(Numbers.java:190)
	at clojure.lang.Numbers.divide(Numbers.java:3911)
	at metabase.server.routes$fn__122320.invokeStatic(routes.clj:51)
```

* Reuse `sql-jdbc.conn/can-connect-with-spec?` for api/health

* Add flag to setting names type

* Add writeback on/off selector

* add react-refresh to webpack dev config

See https://github.com/metabase/metabase/issues/22561 for context.