Notebook(Alerts): have dataset schema, be correctly utilized in the alert thresholds.

## About the bug

**Steps to reproduce:**
List the minimal actions needed to reproduce the behavior.

1. Use the query builder, or raw flux editor, to generate a query using fields.
*
2. Run notebook --> see that the output graph contains data.
3. Build an alert using the fields.
*
4. create a threshold using non-numeric data: `trigger = (r) => r["co"] > 20 and (r["water_level"] > 0 and r["water_level"] < 100) and r["types"] == "earthquake"`
5. Run task get an error --> because used a string field (not a numeric measurement).

.

**Expected behavior:**
I should not be able to create threshold alerts, based on my dataset, which fail when I run the alert task.
* failures due to non-numeric fields (as the example above)
* failures of "never triggered", because user choose a field which exists on another measurement

.

## Proposed solutions:
Either we can:
A. decide to only allow numeric fields to be used in the notebook alerts
B. permit string and numeric fields in threshold checks

### Option A: only allow numeric fields
implementation details:
* data elements:
* https://docs.influxdata.com/influxdb/cloud/reference/key-concepts/data-elements/
* a measurement is a numeric only data element.
* a field has many more types.
* we currently read available `fields` for thresholds, from the returned dataset in the table view.
* The challenge here is that the "field" are actually just table columns --> and do not represent which are measurements or field.
* I believe we have this information already (see that the Error Thresholds have this awareness).

### Option B: permit multiple field types?
implementation details:
* we could start by scoping small (strings and numerics only)
* so make sure we don't have other field types to be aware of
* we would need to stop using the `monitor.check()` method
* this method is already problematic for us. see comment here: https://github.com/influxdata/ui/issues/3707#issuecomment-1064714862
* then use flux like:
```
trigger = (r) => r["co"] > 20 and (r["water_level"] > 0 and r["water_level"] < 100) and r["types"] == "earthquake"

task_data =
from(bucket: "sample_data")
|> range(start: v.timeRangeStart, stop: v.timeRangeStop)
|> filter(fn: (r) => r["_field"] == "co" or r["_field"] == "types" or r["_field"] == "water_level")
|> filter(fn: trigger)
// then send a notification...
```