Add MRecord shape

[breandan]

https://graphviz.org/doc/info/shapes.html#record

[codecov-commenter]

Codecov Report

Merging #178 into master will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##             master     #178   +/-   ##
=========================================
  Coverage     81.63%   81.64%           
  Complexity     1151     1151           
=========================================
  Files           104      104           
  Lines          3605     3606    +1     
  Branches        364      364           
=========================================
+ Hits           2943     2944    +1     
  Misses          461      461           
  Partials        201      201           

Impacted Files	Coverage Δ	Complexity Δ
.../main/java/guru/nidi/graphviz/attribute/Shape.java	100.00% <100.00%> (ø)	3.00 <0.00> (ø)

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[nidi3]

Then, also Record should be added. Records are specially supported with the Records class.