Make GIBBON be a proper/official integrated MATLAB toolbox

[Kevin-Mattheus-Moerman]

I.e. work on toolbox packaging so rather than the custom install script (or complementary to it) work to make GIBBON an toolbox integrated as shown here:
https://uk.mathworks.com/help/matlab/matlab_prog/create-and-share-custom-matlab-toolboxes.html

[vijayiyer05]

Relevant to this issue: the transition to package management is now described in the R2026b prerelease notes.

[martinherrerias]

I've created a matlab.toml and put in in the issue branch.
Also created a test repo with extended notes: https://github.com/martinherrerias/matlab-packaging-test

From what I understand, the matlab.toml is a great step forward from the messy *.prj-based toolbox packaging, but I don't see what advantages it might have (from a CI/CD perspective):

• matlab.toml metadata is ignored by both GitHub-FileExchange integration, and also by mpminstall¹
• It seems still a bit "raw" (not all project features seem supported?)²
• It only works on R2026b (prerelease), which no-one is using, and does not yet run on GitHub actions

We could merge the TOML file into the main branch (I guess it doesn't hurt to have it there), or just worry about it when the promised mpminstall-FileExchange integration is actually working.

@vijayiyer05, are we missing something?

Footnotes

1. Placed a feature request 08888439 ↩

2. Placed a bug report for this 08886969 ↩