feat: create xERC20 template (#5049)

* feat: create xERC20 template

* feat: minor changes

* fix: placeholder text

* fix: add env in title

* feat: add xERC20 label

.github/ISSUE_TEMPLATE/xERC20.md

@@ -0,0 +1,24 @@
+---
+name: New xERC20
+about: This is for whitelisting a new xERC20.
+title: "[TOKEN] [Mainnet/Testnet] xERC20 Whitelisting"
+labels: "xERC20 🪙"
+assignees: ""
+---
+
+## Token Details
+
+- Name: TOKEN
+- Symbol: TKN
+- Chains: Ethereum, Optimism, Arbitrum, Polygon, Gnosis, BSC
+
+## Tasks
+
+- [ ] PR to chaindata: _\<link to PR\>_
+- [ ] PR to monorepo allowlist config: _\<link to PR\>_
+- [ ] Whitelisting complete: _\<link to transaction(s)\>_
+- [ ] PR to Bridge UI: _\<link to PR\>_
+- [ ] PR to Connextscan: _\<link to PR\>_
+- [ ] Lockbox Adapter deployed: _\<link to transaction(s)\>_
+- [ ] Slow path tested: _<link to transfer(s)>_
+- [ ] Router liquidity added and fast path tested: _\<link to transfer(s)\>_