File location for bundled pseudometric

Stream: mathlib4

[Yakov Pechersky]

In #23111 I define a structure of a bundled pseudometric and provide the obvious SemilatticeSup instance on it. I placed the file in Topology/MetricSpace/BundledFun, not very original placement.

Yael reviewed and remarked that it is not the best place for it, and perhaps a folder restructure is the right direction. Bikeshedding question, where should it live, and should the folder be renamed?

https://github.com/leanprover-community/mathlib4/pull/23111#issuecomment-2740379993

I don't hugely like how this new file is under MetricSpace given that it's precisely not about metric spaces! Maybe it should move to a new Topology.Metric folder (and possibly Topology.MetricSpace could become Topology.Metric.Space?)