Update frameguard to sameorigin

[knolleary]

Current helmet/frameguard policy is set to deny - which prevents the app being embedded in an iframe.

This might be causing issues with the immersive editor in production - yet it works on staging. Raising PR to get this change (from deny to sameorigin) and test in a dev env.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 78.72%. Comparing base (dfc4e5a) to head (a2fbbc4). Report is 1 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #4092 +/- ## ======================================= Coverage 78.72% 78.72% ======================================= Files 284 284 Lines 13009 13009 Branches 2897 2897 ======================================= Hits 10241 10241 Misses 2768 2768 ``` | [Flag](https://app.codecov.io/gh/FlowFuse/flowfuse/pull/4092/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=FlowFuse) | Coverage Δ | | |---|---|---| | [backend](https://app.codecov.io/gh/FlowFuse/flowfuse/pull/4092/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=FlowFuse) | `78.72% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=FlowFuse#carryforward-flags-in-the-pull-request-comment) to find out more.

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[knolleary]

Need to get this onto production - it's the only way to ultimate test it properly. Can always revert it necessary is it won't impact anything other than the immersive editor.