Add SQL reference content for InfluxDB 3 Cloud

Cloud pages don't exist yet at the paths below, so [`content/influxdb3/cloud/request-information.md`](https://github.com/influxdata/docs-v2/blob/master/content/influxdb3/cloud/request-information.md) aliases them to a "Request more information" page. Publish the real content and remove the alias.

Closest existing equivalent to source from: `/influxdb3/enterprise/reference/sql/`

## Aliased paths

- [ ] `/influxdb3/cloud/reference/sql/`
- [ ] `/influxdb3/cloud/reference/sql/functions/aggregate/`
- [ ] `/influxdb3/cloud/reference/sql/functions/conditional/`
- [ ] `/influxdb3/cloud/reference/sql/functions/misc/`
- [ ] `/influxdb3/cloud/reference/sql/functions/selector/`
- [ ] `/influxdb3/cloud/reference/sql/functions/time-and-date/`
- [ ] `/influxdb3/cloud/reference/sql/functions/window/`
- [ ] `/influxdb3/cloud/reference/sql/operators/logical/`
- [ ] `/influxdb3/cloud/reference/sql/operators/other/`
- [ ] `/influxdb3/cloud/reference/sql/where/`

## Anchors the new content must provide

Shared content deep-links to these fragments. They're currently faked as hidden ``s in `request-information.md`; remove each span once the real heading exists.

- `#at-time-zone`
- `#date_bin`
- `#date_bin_gapfill`
- `#greatest`
- `#interpolate`
- `#keywords`
- `#lag`
- `#lead`
- `#locf`
- `#logical-operators`
- `#to_timestamp`
- `#to_timestamp_micros`
- `#to_timestamp_millis`
- `#to_timestamp_nanos`
- `#to_timestamp_seconds`
- `#to_unixtime`

## Done when

- [ ] Content is published (or the linking shared content is gated for Cloud)
- [ ] The alias is removed from `request-information.md`
- [ ] Any hidden anchor ``s that belonged to these paths are removed
- [ ] `link-checker` passes

Part of #7391.

Start with content/influxdb3/cloud/request-information.md and compare it with /influxdb3/enterprise/reference/sql/. Publish the listed Cloud SQL reference paths, provide the required anchors, remove the alias and related hidden spans, then run link-checker. Confirm the checklist is complete or that shared content is gated for Cloud.

Written by the indexing model from the issue text.