Move projects workbench column to projects_nodes table

[sanderegg]

Current projects table contain a workbench column of JSON type.
This was an easy way out 7 years ago but is now a bottleneck in many ways such as:

• no relations options between the node_id or other useful parts of the workbench and anywhere else in the DB,
• very poor performance when one needs to go through the DB information (1 row of projects contains all the nodes, so changing one node implies always locking the whole project) for patching, deleting nodes,

Nevertheless changing this fact is not a "piece of cake", as the projects table is sadly used by many different parts of oSparc and from many different processes, among others: webserver, director-v2, storage, others??? and multiple test fixtures and probably also other tests

Tasks

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1. ♻️ Extract workbench from projects to projects_nodes table 🗃️ #7010
   a:database a:director-v2 a:webserver +3
   
2. When listing projects nodes from DB, start to use the new projects_nodes DB table #7100
   a:webserver +1
   
3. Remove workbench from projects table #7046
   t:maintenance +1
   

[giancarloromeo]

I will take care of this issue.