Restored plotly hover functionality for plots with multidimensional data

[stevenaleung]

By default, the :hover keyword is initialized to nothing. Therefore, the if statement in plotly_hover!() defaults to true and the :hoverinfo keyword is set to none, which turns off the data label

Splitting the if statement expression into two restores the default data label functionality and preserves the functionality to turn off the data label

Functionality is restored for heatmap, contour, wireframe, and mesh3d

Resolves #2446, resolves #3051

[codecov]

Codecov Report

Merging #4159 (2c54cf9) into master (0f4a0c7) will increase coverage by 0.04%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #4159      +/-   ##
==========================================
+ Coverage   77.46%   77.51%   +0.04%     
==========================================
  Files          28       28              
  Lines        7048     7048              
==========================================
+ Hits         5460     5463       +3     
+ Misses       1588     1585       -3     

Impacted Files	Coverage Δ
src/recipes.jl	63.56% <0.00%> (+0.22%)	⬆️
src/axes.jl	85.71% <0.00%> (+0.22%)	⬆️

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