U.FL RF connector: Added restriction zone

Datasheet: https://www.hirose.com/en/product/document?clcode=CL0331-0472-2-01&productname=U.FL-R-SMT-1(01)&series=U.FL&documenttype=2DDrawing&lang=en&documentid=0000940668

In the datasheet, a cut-out restriction area is specified:

but no more information are given.

APEX MHF I is compatible with this connector. In fact, they have the same footprint. There is more information in its datasheet:

Datasheet: https://www.i-pex.com/sites/default/files/downloads/pdf/2D_MHF_I_RECEPTACLE_20279C31.pdf

This MR adds the area restriction for tracks, planes and vias in that area, and the soldermask (resist in the drawing) opening. 0.01mm is left as a safety margin between zones and the pads.

Inner layers are included in the keepout. Example:

https://www.silabs.com/documents/public/application-notes/an928.2-efr32-series2-layout-design-guide.pdf