platform-mc: discovery FRU data from terminus

As [1], `pldmd` will host Fru D-Bus inventory object path and Fru
`xyz.openbmc_project.Inventory.Decorator.*` D-Bus interfaces of one PLDM
terminus.
[1] https://github.com/openbmc/docs/blob/master/designs/pldm-stack.md#processing-pldm-fru-information-sent-down-by-the-host-firmware

Support getting FRU data from terminus in the terminus discovery phase
and expose FRU data to the Fru D-Bus properties in
`xyz.openbmc_project.Inventory.Decorator.Asset`,
`xyz.openbmc_project.Inventory.Decorator.AssetTag`,
`xyz.openbmc_project.Inventory.Decorator.Compatible` and
`xyz.openbmc_project.Inventory.Decorator.Revision` interfaces of
`xyz/openbmc_project/FruPldm/<Terminus_Name>` D-Bus object path which is
created by `xyz.openbmc_project.PLDM` D-Bus service. The object path
will be available until the endpoint EID is removed from the MCTP
D-Bus.

```
busctl introspect xyz.openbmc_project.PLDM  /xyz/openbmc_project/inventory/system/board/S0
NAME                                               TYPE      SIGNATURE RESULT/VALUE                       FLAGS
org.freedesktop.DBus.Introspectable                interface -         -                                  -
.Introspect                                        method    -         s                                  -
org.freedesktop.DBus.Peer                          interface -         -                                  -
.GetMachineId                                      method    -         s                                  -
.Ping                                              method    -         -                                  -
org.freedesktop.DBus.Properties                    interface -         -                                  -
.Get                                               method    ss        v                                  -
.GetAll                                            method    s         a{sv}                              -
.Set                                               method    ssv       -                                  -
.PropertiesChanged                                 signal    sa{sv}as  -                                  -
xyz.openbmc_project.Inventory.Decorator.Asset      interface -         -                                  -
.BuildDate                                         property  s         ""                                 emits-change writable
.Manufacturer                                      property  s         ""                                 emits-change writable
.Model                                             property  s         "00014003"                         emits-change writable
.PartNumber                                        property  s         ""                                 emits-change writable
.SerialNumber                                      property  s         "000000218"                        emits-change writable
.SparePartNumber                                   property  s         ""                                 emits-change writable
.SubModel                                          property  s         ""                                 emits-change writable
xyz.openbmc_project.Inventory.Decorator.AssetTag   interface -         -                                  -
.AssetTag                                          property  s         ""                                 emits-change writable
xyz.openbmc_project.Inventory.Decorator.Compatible interface -         -                                  -
.Names                                             property  as        0                                  emits-change writable
xyz.openbmc_project.Inventory.Decorator.Revision   interface -         -                                  -
.Version                                           property  s         "x.x.00008.004"                    emits-change writable
xyz.openbmc_project.Inventory.Item.Board           interface -         -                                  -

```
Signed-off-by: Dung Cao <dung@os.amperecomputing.com>
Signed-off-by: Thu Nguyen <thu@os.amperecomputing.com>
Change-Id: I4f8869f8fee0fc0f8a5a5670d9a42fc7f48cc798
diff --git a/common/utils.hpp b/common/utils.hpp
index 05dc4bd..37765ba 100644
--- a/common/utils.hpp
+++ b/common/utils.hpp
@@ -569,5 +569,25 @@
                             const pldm::utils::PropertyValue& value,
                             double* doubleValue);
 
+/** @brief Convert the Fru String bytes from PLDM Fru to std::string
+ *
+ *  @param[in] value - the Fru String bytes
+ *  @param[in] length - Number of bytes
+ *
+ *  @return Fru string or nullopt.
+ */
+std::optional<std::string>
+    fruFieldValuestring(const uint8_t* value, const uint8_t& length);
+
+/** @brief Convert the Fru Uint32 raw data from PLDM Fru to uint32_t
+ *
+ *  @param[in] value - the Fru uint32 raw data
+ *  @param[in] length - Number of bytes
+ *
+ *  @return Fru uint32_t or nullopt.
+ */
+std::optional<uint32_t> fruFieldParserU32(const uint8_t* value,
+                                          const uint8_t& length);
+
 } // namespace utils
 } // namespace pldm