Separate data reading and parsing logic for binary ftrace header parser

Currently, the binary ftrace header parser (BinaryFTraceFileParser
class) has 2 responsibilities: reading the trace header from a byte
stream and converting information from this byte stream into meaningful
data. This commit refactors the binary ftrace header parser to separate
the data reading logic (the logic that reads the bytes stream) from the
data parsing logic (the logic that converts the byte data into
meaningful data). This will allow more complex data reading logic
while keeping the code easy to maintain.

Change-Id: I418ed26ffdc766039d57381ed9e3412b9682f4ac
Signed-off-by: Hoang Thuan Pham <hoang.pham@calian.ca>
Reviewed-on: https://git.eclipse.org/r/c/tracecompass.incubator/org.eclipse.tracecompass.incubator/+/191278
Tested-by: Trace Compass Bot <tracecompass-bot@eclipse.org>
Tested-by: Bernd Hufmann <bernd.hufmann@ericsson.com>
Tested-by: Matthew Khouzam <matthew.khouzam@ericsson.com>
Reviewed-by: Bernd Hufmann <bernd.hufmann@ericsson.com>
Reviewed-by: Matthew Khouzam <matthew.khouzam@ericsson.com>