Added a few changes to query expressions (#51)

- Added the between operator to query expressions.
- Added the using query expression suffix to specify which index to query (or force a scan). This is required if query planning has found multiple indices that can potentially be used.
- Rewrote the types of the query expressions to allow for functions to be defined once, and be useful in queries that result in DynamoDB queries, and evaluation.
- Added some test functions around time and summing numbers.
- Fixed a bug in the del-attr which was not honouring marked rows in a similar way to set-attr: it was only deleting attributes from the first row.
- Added the -to type flag to set-attr which will set the attribute to the value of a query expression.

internal/dynamo-browse/services/scriptmanager/iface.go

@@ -32,6 +32,7 @@ type SessionService interface {
 
 type QueryOptions struct {
 	TableName         string
+	IndexName         string
 	NamePlaceholders  map[string]string
 	ValuePlaceholders map[string]types.AttributeValue
 }

internal/dynamo-browse/services/scriptmanager/modsession.go

@@ -44,6 +44,11 @@ func (um *sessionModule) query(ctx context.Context, args ...object.Object) objec
 			}
 		}
 
+		// Index name
+		if val, isStr := objMap.Get("index").(*object.String); isStr {
+			options.IndexName = val.Value()
+		}
+
 		// Placeholders
 		if argsVal, isArgsValMap := objMap.Get("args").(*object.Map); isArgsValMap {
 			options.NamePlaceholders = make(map[string]string)