This is a list of tasks to coordinate efforts toward using generic rings in flint

• flint update to 3.0 upgrade to flint3 #35848
• autogenerate pxd header files Autogenerate flint headers #36449
• interface flint generic rings (and objects built on them: matrix, polynomial, ...)
• make any sage ring a flint ring so that it can be used in flint constructors

@mezzarobba