[Aptos Framework][Coin standard] Update coin::register to not fail on duplicate registrations

[movekevin]

Description

This prevents explicit coin::is_account_registered checks to avoid failing coin::register calls due to duplicate registrations.

Test Plan

Unit tests

[lightmark]

We should adopt this kind of logic everywhere instead of abort.

[github-actions]

✅ Forge suite land_blocking success on ab1e0bd0bad8e77ed90522c2424c5759d8862d37

performance benchmark with full nodes : 6391 TPS, 6221 ms latency, 8700 ms p99 latency,no expired txns
Test Ok

• Grafana dashboard
• Humio Logs
• Test runner output
• Test run is land-blocking

[github-actions]

✅ Forge suite compat success on testnet_2d8b1b57553d869190f61df1aaf7f31a8fc19a7b ==> ab1e0bd0bad8e77ed90522c2424c5759d8862d37

Compatibility test results for testnet_2d8b1b57553d869190f61df1aaf7f31a8fc19a7b ==> ab1e0bd0bad8e77ed90522c2424c5759d8862d37 (PR)
1. Check liveness of validators at old version: testnet_2d8b1b57553d869190f61df1aaf7f31a8fc19a7b
compatibility::simple-validator-upgrade::liveness-check : 7534 TPS, 5155 ms latency, 7300 ms p99 latency,no expired txns
2. Upgrading first Validator to new version: ab1e0bd0bad8e77ed90522c2424c5759d8862d37
compatibility::simple-validator-upgrade::single-validator-upgrade : 4673 TPS, 8832 ms latency, 11500 ms p99 latency,no expired txns
3. Upgrading rest of first batch to new version: ab1e0bd0bad8e77ed90522c2424c5759d8862d37
compatibility::simple-validator-upgrade::half-validator-upgrade : 4833 TPS, 8719 ms latency, 11200 ms p99 latency,no expired txns
4. upgrading second batch to new version: ab1e0bd0bad8e77ed90522c2424c5759d8862d37
compatibility::simple-validator-upgrade::rest-validator-upgrade : 6535 TPS, 6042 ms latency, 9900 ms p99 latency,no expired txns
5. check swarm health
Compatibility test for testnet_2d8b1b57553d869190f61df1aaf7f31a8fc19a7b ==> ab1e0bd0bad8e77ed90522c2424c5759d8862d37 passed
Test Ok

• Grafana dashboard
• Humio Logs
• Test runner output
• Test run is land-blocking