Add a reusable test suite

[lkdvos]

This PR defines a more reusable testsuite to allow downstream packages like SUNRepresentations.jl or CategoryData.jl to have a more robust and up to date testing framework, without having to duplicate all of the code.

Additionally, since this package defines an interface, it does make sense that it should also define the tests to verify whether or not an implementation adheres to that interface.
Overall this should make it easier to define new sector types for which we are confident that they work with TensorKit.

I additionally added:

• tests for compatibility of dimensions and fusion rules
• the generic fusion update for the CGC orthogonality relations (see Representations of alternating group of degree 4 #43)

I've tested this, and at least locally the following workflow seems to work very well:

import TensorKitSectors
testsuite_path = joinpath(dirname(dirname(pathof(TensorKitSectors))), "test", "testsuite.jl")
include(testsuite_path)

using CategoryData
I = Object{CategoryData.Fib}

julia> SectorTestSuite.test_sector(I)
Test Summary: | Pass  Total  Time
Object{Fib}   |   94     94  2.0s

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For now, I've left the multi-fusion tests for follow-up work, since this wasn't entirely obvious how to fit that in without making large changes, as there are quite a few hard-coded things in there.

[codecov]

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✅ All modified and coverable lines are covered by tests.

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[Jutho]

Looks perfect to me!