progress towards decoupling cec and cdc functionality, et-al

[Inspirati]

decouple cec user control name strings from both config and log modules

• allows cec-log to exist independent of the application configuration (cec-config) functionality
• cec-log could readily be minimised to not support higher level cec user control specific support
• cec-config need know nothing else about the cec logging capability (this may warrant a re-think)
• cec-config just needs access to a string table which it doesn't make sense to own

move and rename function cec_get_uptime_ms() to cec_log_uptime_ms()

• usb-cdc is already a client of cec-log
• function is not referenced in cec-task
• as for the name, it really isn't even cec specific in any way, but is the timebase for log entries
• usb-cdc only uses it to display stats on the console where the log outputs
• perhaps it should migrate to a lower platform specific layer, as its implementation specific anyhow, we just don't have that layer defined as yet

decouple cec-log from usb-cdc by initialising with pointer to the log function

• cec-log need not have anything to do with the usb layer(s)

also sneak a few other dependency (.h inclusion) reductions in

todo: cec-config contains code which is foreign from pure cec requirements

todo: recently introduced include/config.h may somehow conflict/override with pico-sdk having same

todo: address issue of _CDC_BR being the only thing left requiring inclusion of usb-cdc.h in certain cec modules

[gkoh]

@Inspirati Overall, refactor looks good.
I hope you don't mind if I commit to your branch.

I've addressed the config.h issue by moving it to pico-cec/config.h, otherwise it will eventually collide in a surprising way one day.
Perhaps you have a better idea.

Furthermore, I moved the uptime symbol into its own module.
It could also be called port_* ala FreeRTOS naming style and could become the platform specific adapter layer for:

• uptime
• timer manipulation
• isr handling?
• log printing?
  • not functionally different to the callback in this PR

I have not yet tested this on hardware.

[gkoh]

todo: recently introduced include/config.h may somehow conflict/override with pico-sdk having same

Introduced include/pico-cec/config.h to attempt a basic header namespace.
This requires calling modules to #include "pico-cec/config.h" and does avoid the collision with every other config.h out there.

todo: address issue of _CDC_BR being the only thing left requiring inclusion of usb-cdc.h in certain cec modules

Added _LOG_BR, which just maps to _CDC_BR, narrowing the inclusion dependency tree.

I have done a run-time test and things are still working as before.
So, merging it, thanks @Inspirati!