Put some guards on types allowed in TaylorTangents

[oxinabox]

Not a high priority, and I am not sure if we want to do this.
Hopefully it is zero overhead by I am yet to check.

I found a case in the wild where I had screwed this up, by putting a ZeroTangent somewhere that should have gotten a ZeroTangent().
It's possible to screw this up both in Diffractor itself, but also in rule definitions. (though CRTU.jl will protect against the later)
It is nice to error as close to the creation of the bad type as possible to help work out what is triggering it

[codecov]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (b3e4ee0) 55.05% compared to head (7f5d1df) 55.10%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #220      +/-   ##
==========================================
+ Coverage   55.05%   55.10%   +0.04%     
==========================================
  Files          28       28              
  Lines        2810     2813       +3     
==========================================
+ Hits         1547     1550       +3     
  Misses       1263     1263              

Files	Coverage Δ
src/tangent.jl	47.69% <100.00%> (+1.23%)	⬆️

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