Fix handling of tags for nested functions

[carrieedwards]

Describe the bug
Currently, for certain functions, when another function is an argument that returns results, the tags that had been assigned to the resulting series are not included in the final result of the query. This is because some functions do not copy over tags. Some examples of such functions include aliasByNode, alias, and aggregateLine.

Example:

aliasByNode(absolute(testMetric),1))

The resulting tags will currently just include the name tag, and not the absolute tag.