fw_update: add pre-post update conditions

Description:
This commit introduces the concept of pre and post update conditions in
the firmware update process to meet the code-update design[1]. Allow
platform specific systemd units to run before an update starts and
after an update has finished successfully.

A pre-update condition is executed before the firmware update flow
starts, and a failing one aborts the update. A post-update condition is
executed only after the update has succeeded, as defined by the design;
no condition is executed once the update itself has failed.

[1]: https://github.com/openbmc/docs/blob/master/designs/code-update.md#pre-and-post-update-conditions

- Added a new JSON schema for defining pre and post update conditions
- A condition service that needs arguments is configured as a systemd
  template unit and receives all supported named arguments as its
  escaped instance name

Motivation:
The firmware update process may require certain conditions to be met
before and after the update. This feature allows for greater flexibility
and control over the update process, ensuring that the system is in a
valid state before and after the update.

Tested:
Platform: Yosemite 4, Sentinel Dome T2 in slot 1, BIC firmware update
over PLDM (EID 10, ast1030 v2023SD).

- Parameterized post update condition: pldm resolved
  yv4-bic-post-update@.service into the escaped instance
  boardName=Yosemite_4_Sentinel_Dome_T2_Slot_1,applyTime=OnReset,
  systemd job 34591 returned "done" and the update completed.
- Non parameterized pre update condition: pldm started
  yv4-bic-pre-update.service without an instance name, dropping the
  arguments as expected, job 21105 returned "done" and the update
  proceeded into the transfer.
- No condition configured: with both targets omitted for the component,
  both conditions were skipped and the update still completed, so the
  base update flow is unaffected.
- Unit tests pass in the OpenBMC unit test container, with the format
  and cppcheck stages clean.

Not covered on hardware: a condition that fails, a condition unit that
hits its start timeout, and a manager erased while its condition is
still running.

Change-Id: Ie862c8ec6aa41db3239a6e7438953326e99a7bc3
Signed-off-by: Unive Tien <unive.tien.wiwynn@gmail.com>