feat: influx CLI Packager support for explicit schema buckets

[stuartcarnie]

This PR teaches the influx CLI how to export and apply buckets with explicit schema from Cloud 2. The existing CLI subcommands to export and apply templates require a significant amount of logic be duplicated from the server to validate and parse the template prior to upload. Preferably, the template would be passed to the server for parsing and validation and an appropriate response sent to the client to display to the user. Changing this would require significant refactoring of the HTTP and CLI APIs, which is beyond the scope of this feature.

NOTES

The Packager CLI does not show diffs of hierarchical data, so it is unable to show detailed differences when new measurements are added or new columns to an existing measurement. An existing example of this is Dashboards, which are limited to showing only the number of charts (Num Charts column):

influxdb/cmd/influx/template.go

Lines 1358 to 1362 in 00afd95

	printer := diffPrinterGen("Dashboards", []string{"Description", "Num Charts"})
	appendValues := func(id pkger.SafeID, metaName string, v pkger.DiffDashboardValues) []string {
	return []string{metaName, id.String(), v.Name, v.Desc, strconv.Itoa(len(v.Charts))}
	}

Following the precedent set by Dashboards, the following UI will be shown when applying changes to a bucket that include schema updates:

• CHANGELOG.md updated with a link to the PR (not the Issue)
• Well-formatted commit messages
• Rebased/mergeable
• Tests pass

[stuartcarnie]

Rebased due to conflicts

[stuartcarnie]

Rebased due to conflicts