Add flash_procedure for meru
Summary:
As title, oobgrader is failing with:
```
2023-12-04 07:48:34.696630 - Running flash procedure step: /run/flashy/flash_procedure/flash_meru --imagepath /run/upgrade/image --device mtd:flash0
2023-12-04 07:48:36.017120 - flash_procedure exited with non-zero exit code {rs.exit_status}. Run command result: {rs}
2023-12-04 07:48:36.017241 - Command '/run/flashy/flash_procedure/flash_meru --imagepath /run/upgrade/image --device mtd:flash0' exited with non-zero exit code: CommandResult(exit_status=127, stderr='bash: line 1: /run/flashy/flash_procedure/flash_meru: No such file or directoryn', stdout='', exit_signal=None)
```
Test Plan: test_placeholder
Reviewed By: doranand
Differential Revision: D51812322
fbshipit-source-id: cdb249c721aed89206956b3d7d0e0e007d72998b
