Minor code polishing after ECOC'22 demo

See merge request !13

- improved HTTP status code checks

- minor styling improvements in Slice pages

Merge Hackfest material into Develop

See merge request !11

Tutorials cleanup

See merge request !10

Pass on the tutorials to (i) verify that all parts are complete (did not run the installation procedures); (ii) updated instructions on how to select the Python version; (iii) general aestetic changes.

doc/fix: add instructions for ngsdn-tutorial mininet

See merge request !9

- integrated command files
- moved unused command listings to separate folders
- polished data files
- cleaned up TAPI show topology script and context database
- added TFS descriptor files

NetworkX 22 P4 workshop

See merge request !7

fix(device): avoid conversion to canonical bytes

See merge request !8

Also, remove unecessary conditions prior to rule
insert/update/delete operations

Signed-off-by: Georgios P. Katsikas <gkatsikas@ubitech.eu>

- added bearers for Hackfest

- added MockOSM package

- refined TrandportAPIDriver endpoint retrieval
- refined Driver selection

- added "Delete Service" button

- added basic Netconf/OpenConfig server

- added support for json-formatted custom config rules

- updated tapi_app to plot topologies

- updated TAPI exercise

- fix wrong import of TaskScheduler in _ServiceHandlerAPI interface and related files

fix(automation): ztpUpdate loop resolved

See merge request !6

Signed-off-by: Georgios P. Katsikas <gkatsikas@ubitech.eu>

- Removed deprecated Database Model within Service
- Corrected constructor signature of ServiceHandler interface
- Removed unneeded file in L3NMEmulated Service Handler
- Removed unused imports from TAPI Service Handler

- Removed deprecated PathComputationElement class
- Migrated old L3NMOpenConfig Service Handler to the new framework
- Removed unneeded file in L3NMEmulated Service Handler

OpenConfig Driver:
- added default endpoint type in case it cannot be retrieved from the remote device
- corrected network_instance/edit_config.xml template; wrong XML format