## Description
* Added Meta webhook HMAC validation in meta_token_verify_concern.rb.
* Wired it into instagram_controller.rb and whatsapp_controller.rb.
* WhatsApp now verifies X-Hub-Signature-256 with WHATSAPP_APP_SECRET.
* Instagram now verifies with either FB_APP_SECRET or
INSTAGRAM_APP_SECRET.
* Updated request specs so missing/invalid signatures return 401 and
valid signatures still enqueue jobs.
Fixes # (issue):
[CW-6786](https://linear.app/chatwoot/issue/CW-6786/ghsa-7rw7-pc8v-mrr3-unauthenticated-message-injection-via-missing)
## Type of change
Please delete options that are not relevant.
- [x] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality not to work as expected)
- [ ] This change requires a documentation update
## How Has This Been Tested?
* Updated the controller specs and ran them successfully.
* The original issue is no longer reproducible.
## Checklist:
- [x] My code follows the style guidelines of this project
- [x] I have performed a self-review of my code
- [ ] I have commented on my code, particularly in hard-to-understand
areas
- [ ] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [x] I have added tests that prove my fix is effective or that my
feature works
- [x] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged and published in downstream
modules
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Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>