GetBIOSTable responder implementation

This commit implements the GetBIOSTable responder handler
for the BIOS Enumeration type.
One of the tables among String table, Attribute table and Attribute
Value Table are created/fetched and sent to PLDM requester as response to
the command.

Tested:
Following are the tables constructed from the sample json file present at
"test/bios_jsons/enum_attrs.json"
-bash-4.2$ hexdump -C /tmp/AllBiosTables/stringTable
00000000  00 00 07 00 41 6c 6c 6f  77 65 64 01 00 10 00 43  |....Allowed....C|
00000010  6f 64 65 55 70 64 61 74  65 50 6f 6c 69 63 79 02  |odeUpdatePolicy.|
00000020  00 0a 00 43 6f 6e 63 75  72 72 65 6e 74 03 00 0a  |...Concurrent...|
00000030  00 44 69 73 72 75 70 74  69 76 65 04 00 0a 00 46  |.Disruptive....F|
00000040  57 42 6f 6f 74 53 69 64  65 05 00 0f 00 48 4d 43  |WBootSide....HMC|
00000050  4d 61 6e 61 67 65 64 53  74 61 74 65 06 00 10 00  |ManagedState....|
00000060  49 6e 62 61 6e 64 43 6f  64 65 55 70 64 61 74 65  |InbandCodeUpdate|
00000070  07 00 0a 00 4e 6f 74 41  6c 6c 6f 77 65 64 08 00  |....NotAllowed..|
00000080  03 00 4f 66 66 09 00 02  00 4f 6e 0a 00 04 00 50  |..Off....On....P|
00000090  65 72 6d 0b 00 04 00 54  65 6d 70 00 37 90 c0 da  |erm....Temp.7...|
000000a0
-bash-4.2$ hexdump -C /tmp/AllBiosTables/attributeTable
00000000  00 00 00 01 00 02 02 00  03 00 01 00 01 00 00 04  |................|
00000010  00 02 0a 00 0b 00 01 00  02 00 00 05 00 02 08 00  |................|
00000020  09 00 01 01 03 00 00 06  00 02 00 00 07 00 01 00  |................|
00000030  3b 85 69 a7                                       |;.i.|
00000034
-bash-4.2$ hexdump -C /tmp/AllBiosTables/attributeValueTable
00000000  00 00 00 01 00 00 00 00  d9 f6 42 58              |..........BX|
0000000c

Change-Id: I06aebcc2c2deea66e867fb775afa76a1e5d18dca
Signed-off-by: Sampa Misra <sampmisr@in.ibm.com>