Add new terrian (autotile) templates for square and isometric

[ShatReal]

six new templates: match sides square match corners square match corners and sides square match sides isometric match corners isometric match corners and sides isometric

also corrected the stuff about it being equivalent to 3x3, 3x3 minimal, and 2x2

Bugsquad edit: followup to https://github.com/godotengine/godot-docs/pull/6760

[mhilbrunner]

cc @Calinou

[ghost]

Well shoot I think I accidentally closed this

[ghost]

Okay this pull request is probably superseded by #7789 so I'll be leaving it closed