Add RawPacketBase as common base class between raw packet implementations.

[Dimi1010]

Part of #1899

This PR adds a class RawPacketBase that is to work as a common base class between RawPacket and MBufRawPacket.
The current iteration only takes over the management for timestamp and linkLayer as a minimal example, without defining common API yet.

The class is defined in the internal namespace while in development, with the eventual goal to be "published" to the main namespace when complete.

[codecov]

Codecov Report

❌ Patch coverage is 89.74359% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.80%. Comparing base (5bc893d) to head (7a7917b).

Files with missing lines	Patch %	Lines
Packet++/src/RawPacket.cpp	85.71%	3 Missing ⚠️
Packet++/header/RawPacket.h	94.44%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #1900      +/-   ##
==========================================
- Coverage   82.81%   82.80%   -0.01%     
==========================================
  Files         291      291              
  Lines       51596    51601       +5     
  Branches    11448    11241     -207     
==========================================
  Hits        42730    42730              
- Misses       7708     8048     +340     
+ Partials     1158      823     -335     

Flag	Coverage Δ
alpine320	74.57% <80.95%> (-0.01%)	⬇️
fedora42	74.70% <80.95%> (-0.01%)	⬇️
macos-13	81.02% <89.65%> (-0.01%)	⬇️
macos-14	81.02% <89.65%> (-0.01%)	⬇️
macos-15	81.02% <89.65%> (-0.01%)	⬇️
mingw32	69.82% <55.00%> (-0.06%)	⬇️
mingw64	69.79% <55.00%> (-0.07%)	⬇️
npcap	84.73% <93.54%> (-0.09%)	⬇️
rhel94	74.42% <80.95%> (-0.04%)	⬇️
ubuntu2004	58.74% <70.58%> (+0.02%)	⬆️
ubuntu2004-zstd	58.84% <70.58%> (-0.01%)	⬇️
ubuntu2204	74.35% <80.95%> (-0.01%)	⬇️
ubuntu2204-icpx	60.75% <89.65%> (+<0.01%)	⬆️
ubuntu2404	74.60% <80.95%> (-0.02%)	⬇️
ubuntu2404-arm64	74.59% <80.95%> (+<0.01%)	⬆️
unittest	82.80% <89.74%> (-0.01%)	⬇️
windows-2022	84.71% <93.54%> (-0.09%)	⬇️
windows-2025	84.83% <93.54%> (-0.02%)	⬇️
winpcap	84.95% <93.54%> (-0.01%)	⬇️
xdp	51.28% <71.42%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.