Review UI static files caching

[dapplion]

Some users have reported errors caused because the UI and the DAPPMANAGER versions go out of sync. I've already implemented measures to fight it such as

• Force reload when DAPPMANAGER changes version. https://github.com/dappnode/DNP_DAPPMANAGER/blob/a73faef142d0fd15841741d6977abb0ad542ebc6/packages/admin-ui/src/api/subscriptions.ts#L46 Does this still work? I got a deprecated notice in my Visual Studio code

To review this issue:

• test if the static files cache policy is properly set and the index gets refreshed when the version changes
• research if most browsers supports that policy and find an optimal one. Then add it to the DAPPMANAGER's expressJS static file server.
• If this cannot be solved, make the UI aware that the versions have gone out of sync somehow.

[pablomendezroyo]

@mateumiralles can you follow this research?