Refactor BusWire driver API to use OO driver handles

There was a desire to make the resolved-wire API more object-oriented and easier to read at call sites. Instead of passing a driver identifier into every wire operation, drivers are now registered against wires through a Bus, which binds each driver to per-wire handles.
This adds some setup and indirection internally: the bus topology is declared up front, and each BusDriver gets real per-wire attributes via setattr() so call sites can use controller.sda directly. The underlying wire model still tracks driver state internally, but callers no longer pass string/enum driver names for each operation.

Old:

self._sda.release(I3CBusDriver.CONTROLLER)

New:

self._controller.sda.release()

The refactor removes the old string-based driver API, validates wire/driver names during Bus construction, and keeps the existing resolution/clash-detection behavior unchanged.

There are tradeoffs. The new API makes the operation site nicer and more self-describing, but it adds more objects, upfront bus binding, and some internal indirection. To support the controller.sda style without getattr, the implementation uses setattr() to expose bound wire handles as real attributes on each BusDriver. The underlying wire model still tracks per-driver state internally.

One alternative would be index-based access, for example controller[SDA].release() or controller.wire(SDA).release(). That would avoid dynamic attributes and the Python-identifier restriction on wire names, but it is less readable for protocol wires like scl/sda.

So this PR is partly a design tradeoff: if the extra setup and indirection are not worth the cleaner call sites, we may decide to keep the older string/enum-based API instead as it is flatter and easier to understand internally.