Add Aqua tests and fix unbound type parameters

[devmotion]

The PR adds Aqua tests. On master, both the tests for method ambiguities and for unbound type parameters are broken. I fixed the unbound type parameters in this PR but the method ambiguity issues are not resolved.

[kalmarek]

@devmotion thanks for those tests using Aqua! the reported overwrites seem to be real and we need to find them

[Joel-Dahne]

Thesis submitted, so now I have some time to take a look at this!

In total there are 28 ambiguities, they can be broken up into a few different categories:

• Base._fast (4 ambiguities). We can add explicit cases. I also noticed some other issues with the code when looking at it.
• (::Type{T})(x::Base.TwicePrecision) where T<:Number (6 ambiguities). We have to add an explicit case for this.
• (::Type{T})(x::AbstractChar) where T<:Union{AbstractChar, Number} (6 ambiguities). Same as the above one.
• (::Type{T})(x::Rational{S}) where {S, T<:AbstractFloat} (2 ambiguities). I have not been able to trigger this issue. See below.
• (::Type{T})(z::Complex) where T<:Real (3 ambiguities). I didn't even know that this constructor existed. We can add explicit cases for it. Should we add a case for (::Type{T})(z::Acb where T<:Real also?
• ^(::Irrational{:ℯ}, x::Number) (3 ambiguities). I had forgotten about this method, we can add explicit cases for it.
• 4 ambiguities related to +, * and ^. It fails for AcbSeries()^ArbSeries(), but I have not been able to trigger the other cases. See below.

So there are some ambiguities that I have not been able to trigger, I'm probably missing something. They are:

Ambiguity #1
*(p::Union{Arblib.AcbPoly, Arblib.AcbSeries}, c::Number) @ Arblib ~/Syncthing/Work/Code/Arblib.jl/src/poly.jl:465
*(c::Number, p::Union{Arblib.AcbPoly, Arblib.AcbSeries, Arblib.ArbPoly, Arblib.ArbSeries}) @ Arblib ~/Syncthing/Work/Code/Arblib.jl/src/poly.jl:517

Possible fix, define
  *(::Arblib.AcbSeries, ::Union{Arblib.AcbSeries, Arblib.ArbSeries})

Ambiguity #2
+(p::Union{Arblib.AcbPoly, Arblib.AcbSeries}, c::Number) @ Arblib ~/Syncthing/Work/Code/Arblib.jl/src/poly.jl:439
+(c::Number, p::Union{Arblib.AcbPoly, Arblib.AcbSeries, Arblib.ArbPoly, Arblib.ArbSeries}) @ Arblib ~/Syncthing/Work/Code/Arblib.jl/src/poly.jl:516

Possible fix, define
  +(::Arblib.AcbSeries, ::Union{Arblib.AcbSeries, Arblib.ArbSeries})

Ambiguity #3
^(p::Arblib.ArbSeries, e::Number) @ Arblib ~/Syncthing/Work/Code/Arblib.jl/src/poly.jl:657
^(x::Number, p::Arblib.AcbSeries) @ Arblib ~/Syncthing/Work/Code/Arblib.jl/src/poly.jl:671

Possible fix, define
  ^(::Arblib.ArbSeries, ::Arblib.AcbSeries)

Ambiguity #4
Arblib.Arb(x; prec) @ Arblib ~/Syncthing/Work/Code/Arblib.jl/src/constructors.jl:17
(::Type{T})(x::Rational{S}) where {S, T<:AbstractFloat} @ Base rational.jl:133

Possible fix, define
  Arblib.Arb(::Rational{S}) where S

Ambiguity #5
Arblib.Arf(x; prec) @ Arblib ~/Syncthing/Work/Code/Arblib.jl/src/constructors.jl:11
(::Type{T})(x::Rational{S}) where {S, T<:AbstractFloat} @ Base rational.jl:133

Possible fix, define
  Arblib.Arf(::Rational{S}) where S

My attempts at triggering these are

#1
AcbSeries() * AcbSeries()
AcbSeries() * ArbSeries()

#2
AcbSeries() + AcbSeries()
AcbSeries() + ArbSeries()

#3
AcbSeries()^AcbSeries()

#4
Arb(1 // 2)
Arb(Rational{Int32}(1, 2))

#5
Arf(1 // 2)
Arf(Rational{Int32}(1, 2))

I'm preparing a PR that fixes the easy cases. Then we can see what to do with the rest.

[devmotion]

It would be good to fix these but I thought it would be better to go through them in separate PRs. So I intentionally did not include any fixes in this PR.

[Joel-Dahne]

Yes, I guess we can merge this now then!