chore: Add content security policy

[lenikadali]

Pull Request Template

Description

Adds the content security policy to Chatwoot in line with the guidelines here

for an initial implementation, we are beginning with reports as described here Fixes #404

Type of change

Please delete options that are not relevant.

• [x] Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Not sure how to test this. If indicated by the reviewer, I can come back and update this section accordingly

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my code
• [x] I have commented on my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [ ] I have added tests that prove my fix is effective or that my feature works (also not sure about what test to write for a config file; if need be, I could base the test on this example from GitLab)
• [x] New and existing unit tests pass locally with my changes
• [x] Any dependent changes have been merged and published in downstream modules

[github-actions[bot]]

🐢 Turtley slow progress alert! This pull request has been idle for over 30 days. Can we please speed things up and either merge it or release it back into the wild?

[github-actions[bot]]

🐢 Turtley slow progress alert! This pull request has been idle for over 30 days. Can we please speed things up and either merge it or release it back into the wild?

[bfontaine]

Could someone retrigger the build? It failed on a timeout

[github-actions[bot]]

🐢 Turtley slow progress alert! This pull request has been idle for over 30 days. Can we please speed things up and either merge it or release it back into the wild?

[github-actions[bot]]

🐢 Turtley slow progress alert! This pull request has been idle for over 30 days. Can we please speed things up and either merge it or release it back into the wild?

[lenikadali]

Closing since not needed at the moment.