Decouple local `@stellar/freighter-api` from `@stellar/wallet-sdk`

[piyalbasu]

Problem: if @stellar/wallet-sdk depends on a version of @stellar/freighter-api that matches what is currently in this workspace's package.json, on installation, it will use the symlinked version of freighter-api rather than the published version.

This could lead to issues if we make changes to freighter-api locally that are not published and we attempt to build the extension as wallet-sdk will be using an unpublished/untested version of freighter-api.

Goal: Building the extension always uses published versions of freighter-api as a dependency by default rather than using the local workspace