Added functions to print jacobian matrix in COO to matrix market

[shakedregev]

Description

This is a new feature that enables exporting ScaleMicrogrid examples of arbitrary size for testing.

Proposed changes

The functions work as intended and the rest of the code is intact. This is a broad fix that can work for other Jacobians or COO matrices.
After running make, in your build directory, run

./examples/ScaleMicrogrid/scalemicrogridarbitrary <N>

For example

./examples/ScaleMicrogrid/scalemicrogridarbitrary 1000

This will generate a linear system with $36N-2$ variables and constraints.

Checklist

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• All tests pass.
• Code compiles cleanly with flags -Wall -Wpedantic -Wconversion -Wextra.
• The new code follows GridKit™ style guidelines.
• There are unit tests for the new code.
• The new code is documented.
• The feature branch is rebased with respect to the target branch.

Further comments

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why you chose the solution you did and what alternatives you considered, etc...

[pelesh]

Looks good. A few minor changes are recommended for consistency.

Fixed

[shakedregev]

After running make, in your build directory, run

./examples/ScaleMicrogrid/scalemicrogridarbitrary <N>

For example

./examples/ScaleMicrogrid/scalemicrogridarbitrary 1000

This will generate a matrix of size $36N-2$

[pelesh]

Needs to be rebased to develop, otherwise good to merge.