Feature/fbw verbose scanning

[selankon]

Implements necessary logic to show scan results on the frontend:

• Save mesh scan results on a file located at /tmp/fbw/lime-scan-results.json
• Send downloaded configuration files, together with scan results on /ubus/search_networks/
• If a network is selected before scan is finished, stop the scan service and restore the previous wifi configuration before applying the new configuration file
• Append the Ap bssid to the lime configuration file to show on the frontend what lime configuration file is associated to which scanned station. Now, the lime config files shows like: lime-community__host__ql-refu-bbone__38:AB:C0:C1:D6:70
• Send trimmed configuration file sending only "wifi" section, needed for the frontend.

Together with: https://github.com/selankon/lime-app/tree/feature/fbw-show-scan-results

[spiccinini]

Wow! This looks awesome!!

[codecov-commenter]

Codecov Report

Merging #925 (d5169d6) into master (052db0b) will increase coverage by 0.99%. The diff coverage is 80.43%.

:exclamation: Current head d5169d6 differs from pull request most recent head 8745d7b. Consider uploading reports for the commit 8745d7b to get more accurate results

@@            Coverage Diff             @@
##           master     #925      +/-   ##
==========================================
+ Coverage   76.73%   77.72%   +0.99%     
==========================================
  Files          48       48              
  Lines        4074     4144      +70     
==========================================
+ Hits         3126     3221      +95     
+ Misses        948      923      -25     

Impacted Files	Coverage Δ
...rd/files/usr/lib/lua/firstbootwizard/functools.lua	32.00% <33.33%> (-1.79%)	:arrow_down:
...-boot-wizard/files/usr/lib/lua/firstbootwizard.lua	59.18% <80.72%> (+18.47%)	:arrow_up:
...wizard/files/usr/lib/lua/firstbootwizard/utils.lua	42.45% <100.00%> (+0.54%)	:arrow_up:
...kages/lime-system/files/usr/lib/lua/lime/utils.lua	85.20% <0.00%> (+3.84%)	:arrow_up:

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[selankon]

Add features on last commits:

• Verbose fetch configuration errors (example, if can't get lime-community file or the destination node is not configured yet)

[selankon]

Hopefully this is ready to merge among with https://github.com/libremesh/lime-app/pull/339

[selankon]

This come with https://github.com/libremesh/lime-app/pull/334 which is already merged

[spiccinini]

Outstanding work! Thanks!