Rename the path to Forex AMM

[prayagd]

Context

Currently the URL or path to Forex AMM mentions Nabla, this ticket is to fix it and call it forex-amm

Requirement

• Change this to "https://portal.pendulumchain.org/pendulum/nabla/swap" to "https://portal.pendulumchain.org/pendulum/forex-amm/swap"
• This should be done to all sub items i.e swap pool and backstop pool

[prayagd]

Hey team! Please add your planning poker estimate with Zenhub @ebma @Sharqiewicz @TorstenStueber