Warn on extrakws

[isentropic]

Description

Consider a case from https://docs.juliaplots.org/stable/backends/#Fine-tuning

x = range(-3, 3, length=30)
surface(
  x, x, (x, y)->exp(-x^2 - y^2), c=:viridis, legend=:none,
  nx=50, ny=50, display_option=Plots.GR.OPTION_SHADED_MESH,  # <-- series[:extra_kwargs]
)

Upon mispelling of any kws it is interpretted as an extra_kw which leads to silent ignoring of kws:

# before
plot(rand(10), newweirdarg=true)

just plots.
Now it outputs:

 Warning: Extra keyword argument newweirdarg not explicitly supported with Plots.GRBackend().  Choose from: legend_hfactor, legend_wfactor, nx, ny, display_option
└ @ Plots ~/Projects/Plots.jl/src/args.jl:1564

Granted this is a crutch as I just look over a list of predefined kws, but in principle this mechanism could be more sophisiticated per backend. What you think?

[BeastyBlacksmith]

In principle I am on board with the idea, but e.g. the PGFPlotsX backend makes deliberate use of this as in it passes all extra keywords to the backend and they usually just work.
See #2200 for reference. So to get it right, we would need to check against every valid keyword of pgfplots (and keep it up to date).

[isentropic]

We could just ignore this check for PGF plots, it could just support all of them. I understand that you might wanna add more tex there.
But other backends aren't as much flexible

[BeastyBlacksmith]

Yeah, if we make the check use a predicate function, that could just return true in that case

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.58%. Comparing base (fa65e7d) to head (8bf9d59).
Report is 17 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4861      +/-   ##
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- Coverage   89.77%   89.58%   -0.19%     
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  Files          40       40              
  Lines        8780     8787       +7     
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- Hits         7882     7872      -10     
- Misses        898      915      +17     

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