expose cesium antialiasing parameter via the UI

[landryb]

Description

as found out by my colleague working on 3d datasets, cesium has an antialiasing parameter named "msaaSamples" since CesiumGS/cesium#10052, cf CesiumGS/cesium#9900 for the background

according to the cesium docs:

If provided, this value controls the rate of multisample antialiasing. Typical multisampling rates are 2, 4, and sometimes 8 samples per pixel. Higher sampling rates of MSAA may impact performance in exchange for improved visual quality. This value only applies to WebGL2 contexts that support multisample render targets. Set to 1 to disable MSAA.

it provides nice rendering improvements when tested via the map plugin config (eg setting "msaaSamples" inside the "cesium" block), especially on 3d buildings with straight lines

without msaasamples:

with msaasamples set to 4

Acceptance criteria

it might be interesting to provide a checkbox or a counter in the 3d view configuration to set the parameter, and make it discoverable to users.