Update Delphyne Guide

Context

Delphyne guide hasn't been updated for a while and lately many changes related to the ignition migration have taken place.

I've created another document based on the first one as it can be modified. Delphyne Guide 2021

Tasks

On code

• Fixes log argument for the demos when no output filename is passed. e.g. delphyne_gazoo --log:
  https://github.com/ToyotaResearchInstitute/delphyne/pull/805
  https://github.com/ToyotaResearchInstitute/delphyne_demos/pull/24
• During ignition migration some files got named with a "2" as suffix. This should be cleaned up: https://github.com/ToyotaResearchInstitute/delphyne_gui/pull/455
• Update Readme file https://github.com/ToyotaResearchInstitute/delphyne/pull/807
• Teleop plugin resize. https://github.com/ToyotaResearchInstitute/delphyne_gui/pull/458
• Fix delphyne_city demo. https://github.com/ToyotaResearchInstitute/delphyne_demos/pull/26
• Fix delphyne_city demo in focal. https://github.com/ToyotaResearchInstitute/delphyne/pull/813
• Fix delphyne_crash demo: https://github.com/ToyotaResearchInstitute/delphyne/issues/808
• Adds smoke tests for all the demos https://github.com/ToyotaResearchInstitute/delphyne_demos/pull/28
• Fix layout selection when running demos. https://github.com/ToyotaResearchInstitute/delphyne_gui/pull/459 https://github.com/ToyotaResearchInstitute/delphyne_demos/pull/29
• Fix gui plugin list https://github.com/ToyotaResearchInstitute/delphyne_gui/issues/460
• Fix text render in the visualizer: https://github.com/ToyotaResearchInstitute/delphyne_gui/issues/469

On document

• Correct naming in the entire document: e.g delphyne-replay --> delphyne_replay
• Update pictures using ign-gui3 based visualizer when necessary.
• Update Build & Installation section which also implies a modification at delphyne's README that is outdated.
• Update Style Checking & Formatting section: cpplint isn't being used.
• Verify code snippets related to Python layer.
• Verify info about Agent Framework.
• Adds an example on how to use the Agent.
• Adds info about BehaviorTree machinery
• Update On the RoadMap section(?)
• Update collision detection snippet code as it doesn't work.
• Update info about PlaybackWidget as it was replaced by PlaybackPlugin.
• Update Manipulating the Time Stream section.
• Plot widget section: It wasn't migrated to ign-gui3. https://github.com/ToyotaResearchInstitute/delphyne_gui/issues/456
• Add info about the teleop plugin
• Add info about the TopicStats plugin
• Add info about the TopicViewer plugin
• Update info about Scene Tree Widget: This plugin was reimplemented as ign-gui3 didn't migrate it from ign-gui0.
• Update Displays Widget section as many were reimplemented.
• Adds info about gui configuration save/load.

Bonus

• This guide probably should be added to maliput_documentation/ delphyne_documentation(if exists in the future)

Start with the linked Delphyne Guide 2021 document and review the two unchecked items: the RoadMap section and the Plot widget section, which references delphyne_gui issue 456. Done means the guide reflects the current project status and documents the relevant widget state accurately.