AEP 01 - Similarity Search Module

[MatthewMiddlehurst]

introduces a similarity search module. See

aeon-toolkit/aeon#724

and the AEP document. Similarity search is a primitive of many operations, so the design is a bit unclear. We would like to get this first version in then consider the use cases. It may be we dont need a base class and can represent it as a bunch of functions like distances would be good to consider the use cases here (list more below)

1. As a task in its own right: the basic query operation seems valid. The general research issue as I understand it is how to approximate Euclidean distance for subseries matching much faster than niavely iterating. Includes lower bounding
2. Matrix profile is essentially a nearest neighbour search
3. Shapelet and covolutions both need subseries matching

[MatthewMiddlehurst]

First PR in aeon proper is at aeon-toolkit/aeon#724.

I think we should keep this open until it has been finalised a bit more (i.e. no longer experimental) and add onto it.