Refactor CFE_FS_SetTimestamp and eliminate typo

[skliper]

Is your feature request related to a problem? Please describe.
There's a typo in one of the syslogs:

cFE/modules/fs/fsw/src/cfe_fs_api.c

Line 275 in 73c338d

CFE_ES_WriteToSysLog("CFE_FS:SetTime-Failed to write Seconds (Status=0x%08X)\n", (unsigned int)Result);

Also could just write the time structure instead of seconds and then subseconds:

cFE/modules/fs/fsw/src/cfe_fs_api.c

Lines 262 to 281 in 73c338d

	Result = OS_write(FileDes, &OutTimestamp.Seconds, sizeof(OutTimestamp.Seconds));
	/* On a good write, the value returned will equal the number of bytes written */
	if (Result == sizeof(OutTimestamp.Seconds))
	{
	Result = OS_write(FileDes, &OutTimestamp.Subseconds, sizeof(OutTimestamp.Subseconds));
	if (Result == sizeof(OutTimestamp.Subseconds))
	{
	Result = OS_SUCCESS;
	}
	else
	{
	CFE_ES_WriteToSysLog("CFE_FS:SetTime-Failed to write Seconds (Status=0x%08X)\n", (unsigned int)Result);
	}
	}
	else
	{
	CFE_ES_WriteToSysLog("CFE_FS:SetTime-Failed to write Seconds (Status=0x%08X)\n", (unsigned int)Result);
	}

Describe the solution you'd like
Write time structure, one syslog with an updated message.

Describe alternatives you've considered
None

Additional context
Code review

Requester Info
Jacob Hageman - NASA/GSFC