dbt modeling guidance docs (#2874)

* start working on modeling decisions flowchart

* fix admonition

* fix single quotes

* expand on bug identification and test linking

* fixing bugs, grain overview

* fix box type and more docs

* example testing

* add testing, documentation docs

* fix links

* rephrase some things, finish flowchat

* fix emoji breaking mermaid and add callout about incremental models

* add example stakeholder doc and rearrange a bit

* move incremental warning, a few more tweaks

* actually move incremental warning

* pr comments

* add loom links for debugging a failing test

* reorder

* tweak video link name

* clarify bug types

* more clarifications, esp for incremental models

* linter

* reference correct github action