feat: Bridge.begin waits to be greenlighted by MPU up to timeout

[eigen-value]

This PR is open to discussion and is an alternative proposal to #32

• It ensures Bridge operations (calls / provide user defined methods) only after Router is really UP, signaling via the "greenLight" method
• Waits for a semaphore up to a given timeout so it is backwards compatible

[github-actions]

Memory usage change @ da47799

Board	flash	%	RAM for global variables	%
arduino:zephyr:unoq	🔺 +2172 - +3548	+0.11 - +0.18	🔺 +24 - +24	0.0 - 0.0

Click for full report table

Board	examples/client flash	%	examples/client RAM for global variables	%	examples/clientSSL flash	%	examples/clientSSL RAM for global variables	%	examples/hci flash	%	examples/hci RAM for global variables	%	examples/monitor flash	%	examples/monitor RAM for global variables	%	examples/server flash	%	examples/server RAM for global variables	%	examples/simple_bridge flash	%	examples/simple_bridge RAM for global variables	%	examples/test flash	%	examples/test RAM for global variables	%	examples/test_rpc_thread flash	%	examples/test_rpc_thread RAM for global variables	%	examples/udp_ntp_client flash	%	examples/udp_ntp_client RAM for global variables	%
arduino:zephyr:unoq	2848	0.14	24	0.0	3112	0.16	24	0.0	2648	0.13	24	0.0	2172	0.11	24	0.0	2944	0.15	24	0.0	2428	0.12	24	0.0	3100	0.16	24	0.0	N/A	N/A	N/A	N/A	3548	0.18	24	0.0

Click for full report CSV

Board,examples/client<br>flash,%,examples/client<br>RAM for global variables,%,examples/clientSSL<br>flash,%,examples/clientSSL<br>RAM for global variables,%,examples/hci<br>flash,%,examples/hci<br>RAM for global variables,%,examples/monitor<br>flash,%,examples/monitor<br>RAM for global variables,%,examples/server<br>flash,%,examples/server<br>RAM for global variables,%,examples/simple_bridge<br>flash,%,examples/simple_bridge<br>RAM for global variables,%,examples/test<br>flash,%,examples/test<br>RAM for global variables,%,examples/test_rpc_thread<br>flash,%,examples/test_rpc_thread<br>RAM for global variables,%,examples/udp_ntp_client<br>flash,%,examples/udp_ntp_client<br>RAM for global variables,%
arduino:zephyr:unoq,2848,0.14,24,0.0,3112,0.16,24,0.0,2648,0.13,24,0.0,2172,0.11,24,0.0,2944,0.15,24,0.0,2428,0.12,24,0.0,3100,0.16,24,0.0,N/A,N/A,N/A,N/A,3548,0.18,24,0.0