[be1] reorganize files

[sgueissa]

It is the first PR of cleaning and other PRs will come. Next PR will be creating a global error type and removing the *answer.Error return type.

1. Moved all the old backend inside the directory old
2. Moved all the files inside internal but cli
3. Break the handler package in Query, Answer and Channel package to prepare for the incoming ref injection and top to bottom building in a future PR
4. Update the doc

[github-actions]

Pull reviewers stats

Stats of the last 30 days for popstellar:

	User	Total reviews	Time to review	Total comments
	K1li4nL 🥇	10 ▀▀▀	4d 20h 56m ▀	12 ▀▀▀
	simone-kalbermatter 🥈	4 ▀	8h 40m	0
	onsriahi14 🥉	4 ▀	1d 23h 8m ▀	4 ▀
	matteosz	3 ▀	4d 40m ▀	5 ▀
	pierluca	2 ▀	3d 11h 3m ▀	1
	arnauds5	2 ▀	5d 15h 3m ▀▀	0
	DanielTavaresA	2 ▀	2d 10h 22m ▀	8 ▀▀
	quadcopterman	2 ▀	6d 13h 46m ▀▀	1
	Tyratox	1	44m	0
	sgueissa	1	6d 11h 44m ▀▀	1
	osm-alt	1	25m	0
	emonnin-epfl	1	51m	1
	Kaz-ookid	1	1d 2h 1m	5 ▀
⚡️ Pull request stats

[emonnin-epfl]

I think mocks should be renamed mock since all packages are singular (expect types which will be removed later). You changed the high and low packages as we discussed on WhatsApp which is great and same thing for renaming fake_socket to socket.

Overall nice job

[sonarcloud]

Quality Gate passed for 'PoP - PoPCHA-Web-Client'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarCloud

[K1li4nL]

blind approval

[sonarcloud]

Quality Gate passed for 'PoP - Be2-Scala'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarCloud

[sonarcloud]

Quality Gate failed for 'PoP - Be1-Go'

Failed conditions
33.3% Coverage on New Code (required ≥ 65%)
1 New Critical Issues (required ≤ 0)

See analysis details on SonarCloud

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[sonarcloud]

Quality Gate passed for 'PoP - Fe1-Web'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarCloud

[sonarcloud]

Quality Gate passed for 'PoP - Fe2-Android'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarCloud