Small updates to BTAS

[kmp5VT]

Some factors need to be implemented more universally, such as the generate random matrix function. A few new convergence checkers such as, no checking and two that look at the difference between approximations between iterations, instead of the global fit.

TODO

• [ ] Make more unit tests for these methods.
• [ ] Remove some unnecessary artifacts.

[evaleev]

@kmp5VT does this need the TODOs to be completed?

[kmp5VT]

@evaleev I updated the unit-tests for the new features so this should be ready to merge, provided CI has no issues.