[BE1] Upgrade gossip rumor with vector clock

[sgueissa]

In this PR we did:

1. Rumor Push protocol with vector clock
2. Buffer inside Rumor handler to handle cases where a newer rumor is arriving few second before an older rumor
3. Rumor Pull protocol with vector clock
4. Fix order of the answer to catchup query

[github-actions[bot]]

Pull reviewers stats

Stats of the last 30 days for popstellar:		User	Total reviews	Time to review	Total comments
	K1li4nL 🥇	20 ▀▀▀▀	1d 19h 44m)) ▀	10 ▀▀
	arnauds5 🥈	6 ▀	18h 5m))	4 ▀
	emonnin-epfl 🥉	5 ▀	8h 20m))	9 ▀▀
	onsriahi14	4 ▀	1d 1h 53m)) ▀	4 ▀
	simone-kalbermatter	3 ▀	1h 47m))	0
	matteosz	3 ▀	14h 5m))	3 ▀
	pierluca	2	3d 11h 3m)) ▀▀	1
	sgueissa	2	1d 12h 28m)) ▀	4 ▀
	MariemBaccari	2	22h 39m))	6 ▀
	DanielTavaresA	2	9d 21h 46m)) ▀▀▀▀▀	2

^{⚡️ Pull request stats}

[sonarcloud[bot]]

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

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[sonarcloud[bot]]

Quality Gate passed for 'PoP - Be2-Scala'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[sonarcloud[bot]]

Quality Gate passed for 'PoP - Be1-Go'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
68.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[sgueissa]

LVGTM!

YOU TOO!!!

[sonarcloud[bot]]

Quality Gate passed for 'PoP - Fe2-Android'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud