Initial support for FileIO

[rakeshksr]

This PR adds support for FileIO.jl and Base.show method for OpenCV.Mat format.
Awaiting JuliaIO/FileIO.jl#381 to merge.
Covers most of #34.
Closes #30 .

[rakeshksr]

Image preview working fine Pluto.jl, Ijulia and VS Code.

VS Code

Pluto.jl

IJulia

[rakeshksr]

@ashwani-rathee
The PR JuliaIO/FileIO.jl#381, which this PR relied on, has been successfully merged. With that dependency out of the way, I'd be grateful if you could take a look at this PR

[rakeshksr]

@ashwani-rathee Gentle bump

[codecov]

Codecov Report

Attention: Patch coverage is 16.12903% with 26 lines in your changes are missing coverage. Please review.

Project coverage is 16.12%. Comparing base (03b605d) to head (6a189ca).

Files	Patch %	Lines
src/fileio.jl	17.85%	23 Missing ⚠️
src/show.jl	0.00%	3 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##            master      #35       +/-   ##
============================================
- Coverage   100.00%   16.12%   -83.88%     
============================================
  Files            1        2        +1     
  Lines            1       31       +30     
============================================
+ Hits             1        5        +4     
- Misses           0       26       +26     

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