fix NEO-M8 symbol and package

[martin-c]

The following changes were made to the NEO-M8 symbol:

• update symbol layer to "symbols"
• add component name and value fields
• enable pin numbering in pin symbol, remove redundant numbers in pin name
• group pins based on logical operation in component
• center and trim symbol
• add bar(inverse) markup to names with _N suffix
• add _N and _P to USB pin names to enable differential pair routing

The following changes were made to the NEO-M8 package:

• center the package on the origin
• remove default paste stencil openings, add openings according to UBX-15029985-R03 section 2.3 and IPC-7351C
• add tDocu symbols to show location of solderpads on module
• add part name and value (default value sent in component attributes)
• add tKeepout polygon over module footprint