Add error hints for package extensions

[ph-kev]

closes #15 - This PR adds error hints for functions in the package extensions.

For example, if you run this

import ClimaAnalysis.Visualize as viz
import ClimaAnalysis
import Makie
using OrderedCollections
long = 0.0:180.0 |> collect
lat = 0.0:90.0 |> collect
data2D = reshape(1.0:(91 * 181), (181, 91))
dims2D = OrderedDict(["lon" => long, "lat" => lat])
attribs = Dict([
    "short_name" => "name",
    "units" => "units"
])
dim_attributes2D = OrderedDict([
    "lon" => Dict(["units" => "degrees"]),
    "lat" => Dict(["units" => "degrees"]),
])
var2D = ClimaAnalysis.OutputVar(attribs, dims2D, dim_attributes2D, data2D)
fig = Makie.Figure()

viz.heatmap2D_on_globe!(fig, var2D)

Then, you get the error

ERROR: MethodError: no method matching heatmap2D_on_globe!(::Makie.Figure, ::ClimaAnalysis.Var.OutputVar{Vector{…}, Base.ReshapedArray{…}, String, Dict{…}})
The function `heatmap2D_on_globe!` exists, but no method is defined for this combination of argument types.
Import GeoMakie to enable `heatmap2D_on_globe!`. You might also need to import Makie and its backends (CairoMakie, GLMake, etc.) as well.

[codecov]

Codecov Report

Attention: Patch coverage is 60.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 98.19%. Comparing base (e4494a8) to head (5154e23).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/Visualize.jl	60.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #184      +/-   ##
==========================================
- Coverage   98.35%   98.19%   -0.16%     
==========================================
  Files          11       12       +1     
  Lines        1215     1220       +5     
==========================================
+ Hits         1195     1198       +3     
- Misses         20       22       +2     

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[Sbozzolo]

We should split and return the precise package that needs to be leaded (ie, a Makie backend or GeoMakie)

Also, I don't know if it helps but there's a Base.get_extension function that directly checks if the extension has been loaded. I am not sure if there's any advantage with respect to using is_pkg_loaded

[ph-kev]

It is possible to use Base.get_extension instead of is_pkg_loaded. For this particular case, it doesn't matter since you just need to load in one package to enable the extension. However, if an extension requires multiple packages to be loaded, then just checking the extension means you don't know what packages are loaded or are not loaded.

[Sbozzolo]

Makes sense, thank you!

[Sbozzolo]

Thank you!