Migrate PFM to `ibc-apps` repo

[agouin]

Packet forward middleware should be added to ibc-apps with an accompanying sim app (to be created, can reference implementations such as noble, juno, osmosis) and interchaintest case

[boojamya]

Waiting on backporting. Assigning: @boojamya

[boojamya]

Backporting done ✔️

[jtieri]

Backporting done ✔️

Awesome! I should get PFM fully migrated next week as I will be OOO half of tomorrow and all of Friday.

[jtieri]

This has been completed ✅

• v7
• v6
• v5
• v4

At this point I think we should consider the v3 branch here unsupported given ibc-go/v3 has been EOL for awhile, so it doesn't make sense to move v3 to the ibc-apps repo as we don't even maintain a release/v3 branch there.

I have also opened up an issue here for archiving this repo/pointing users in the right direction for new issues and prs.