Add veneers for panel transformations

[K-Phoen]

Transformations can be quite tedious to define. See:

cog/examples/_go/disk.go

Lines 61 to 136 in fa1fbdc

	WithTransformation(dashboard.DataTransformerConfig{
	Id: "groupBy",
	Options: map[string]any{
	"fields": map[string]any{
	"Value #A": map[string]any{
	"aggregations": []string{"lastNotNull"},
	"operation": "aggregate",
	},
	"Value #B": map[string]any{
	"aggregations": []string{"lastNotNull"},
	"operation": "aggregate",
	},
	"mountpoint": map[string]any{
	"aggregations": []string{},
	"operation": "groupby",
	},
	},
	},
	}).
	WithTransformation(dashboard.DataTransformerConfig{
	Id: "merge",
	Options: map[string]any{},
	}).
	WithTransformation(dashboard.DataTransformerConfig{
	Id: "calculateField",
	Options: map[string]any{
	"alias": "Used",
	"binary": map[string]any{
	"left": "Value #A (lastNotNull)",
	"operator": "-",
	"reducer": "sum",
	"right": "Value #B (lastNotNull)",
	},
	"mode": "binary",
	"reduce": map[string]any{
	"reducer": "sum",
	},
	},
	}).
	WithTransformation(dashboard.DataTransformerConfig{
	Id: "calculateField",
	Options: map[string]any{
	"alias": "Used, %",
	"binary": map[string]any{
	"left": "Used",
	"operator": "/",
	"reducer": "sum",
	"right": "Value #A (lastNotNull)",
	},
	"mode": "binary",
	"reduce": map[string]any{
	"reducer": "sum",
	},
	},
	}).
	WithTransformation(dashboard.DataTransformerConfig{
	Id: "organize",
	Options: map[string]any{
	"excludeByName": map[string]any{},
	"indexByName": map[string]any{},
	"renameByName": map[string]any{
	"Value #A (lastNotNull)": "Size",
	"Value #B (lastNotNull)": "Available",
	"mountpoint": "Mounted on",
	},
	},
	}).
	WithTransformation(dashboard.DataTransformerConfig{
	Id: "sortBy",
	Options: map[string]any{
	"fields": map[string]any{},
	"sort": []map[string]any{
	{"field": "Mounted on"},
	},
	},
	}).

They could use some veneers to make them easier to discover and use.