fboss2: add show reboot-cause and show reboot-cause history commands

[arajeev-ARISTA]

Pre-submission checklist

• I've ran the linters locally and fixed lint errors related to the files I modified in this PR. You can install the linters by running pip install -r requirements-dev.txt && pre-commit install
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Summary

• Adds fboss2 CLI commands to query the reboot_cause_service (port 5974):
  • show reboot-cause: displays the last reboot cause investigation result
  • show reboot-cause history: displays all persisted reboot cause results
• Includes model.thrift for display types, command handlers, CmdList registration, and CliFboss2.cmake build wiring

Dependency: #1141 — platform: add reboot cause service with persistent history; required for the CLI commands to function

Test Plan

Verified fboss2 show reboot-cause and fboss2 show reboot-cause history outputs:

[root@vpr428 ~]# fboss2 show reboot-cause
PSU AC Loss [Provider: MERU800BIA_SMB_CPLD, Time: 04-29-2026 06:16:55.000]
[root@vpr428 ~]#
[root@vpr428 ~]# fboss2 show reboot-cause history
Collection Time         Description                     Provider                Cause Time
----------------------------------------------------------------------------------------
04-29-2026 06:22:12     PSU AC Loss                     MERU800BIA_SMB_CPLD     04-29-2026 06:16:55.000
04-29-2026 06:15:08     PSU AC Loss                     MERU800BIA_SMB_CPLD     04-29-2026 06:06:03.000

[meta-codesync]

@somasun has imported this pull request. If you are a Meta employee, you can view this in D109752077.