Use FiniteHorizonGramians.jl

[nathanaelbosch]

Use FiniteHorizonGramians.jl to compute transition matrices in a numerically more stable manner - and hopefully also more efficiently!

Fixes #256

Left to do:

• [x] Remove unneccessary allocations in FiniteHorizonGramians with this PR: https://github.com/filtron/FiniteHorizonGramians.jl/pull/9
• [x] Get FiniteHorizonGramians.jl registered? EDIT: See https://github.com/filtron/FiniteHorizonGramians.jl/issues/12
• [x] Add some way to pre-allocate all the temporary matrices so that we only need to allocate them once before at the start. EDIT: See https//github.com/filtron/FiniteHorizonGramians.jl/pull/16
• [ ] FastBroadcast.jl? Octavian.jl? Check if these make a difference. But first do the other things above.
• [ ] Benchmark the change! E.g. Rosenbrock-type probabilistic exponential integrator before and after? Would be great to see an improvement! So we shoul also create some benchmark first where this appears.

[codecov[bot]]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (ee6cc36) 93.78% compared to head (59b219c) 92.34%.

:exclamation: Current head 59b219c differs from pull request most recent head 53b7eef. Consider uploading reports for the commit 53b7eef to get more accurate results

Files	Patch %	Lines
src/priors/ltisde.jl	85.71%	3 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #268 +/- ## ========================================== - Coverage 93.78% 92.34% -1.45% ========================================== Files 36 36 Lines 1576 1593 +17 ========================================== - Hits 1478 1471 -7 - Misses 98 122 +24 ```

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