Upgrade the TagComponent to the KnowledgeComponent

[drew2a]

This is a draft PR that upgrades the TagComponent to the KnowledgeGraphComponent with adding a Linux snippet.
Related to #6214

TODO:

• Apply a more generic DB structure for the KG
• Update the networking part of TagCommunity
• Write a migration
• Fix tags case sensitivity
• Rename TagCommunity to KnowledgeCommunity
• Add a type field for Resource
• Created a basic validation experiment to check correctness of the knowledge gossip logic
• Update the REST endpoints to process statements instead of tags

Migration:

1. Remove all received entities
2. Regenerate locally created entities

Questions:

1. How to store the tags database? If we store the Tags DB locally, we will have quick responses for local and remote search queries. The drawback is that this DB will use a lot of disk space (more than 5Gb with infinitive growth). If we store the Tags DB distributively then the usage of disk space will be minimal, but metadata retrieval will become a more complex and time-consuming task.
2. Which mechanism will we use for knowledge retrieval? Just random gossip (like popularity community)?
3. How quickly knowledge spreads across the network?

Ubuntu (1 snippet)

Ubuntu (3 snippets)

Debian and Linux Mint (10 snippets)

Ref:

• https://en.wikipedia.org/wiki/Dublin_Core
• https://en.wikipedia.org/wiki/Resource_Description_Framework
• https://github.com/RDFLib/rdflib

[devos50]

It seems that the Windows tests are failing on tests related to tags: https://github.com/Tribler/tribler/actions/runs/3266579335/jobs/5370515178. Is this expected?

[drew2a]

It seems that the Windows tests are failing on tests related to tags: https://github.com/Tribler/tribler/actions/runs/3266579335/jobs/5370515178. Is this expected?

@devos50 it looks like a bug

[drew2a]

@devos50 the Windows tests are fixed!

[kozlovsky]

For me the PR looks good

[synctext]

With this pull request we put Tribler on the path of P2P-style "semantic search".