Add Gname.com dnsapi support

[GNDevProd]

This PR adds a DNS API plugin for GNAME.com (Gname.com Pte. Ltd.).
Supports ACME DNS-01 TXT record management (adds/removes _acme-challenge TXT records)
Uses the official API :
https://www.gname.com/domain/api
Saves credentials to account.conf for non-interactive renewals (per DNS-API-Dev-Guide)

The API needs to be granted [Domain Management] and an IP whitelist needs to be set up on the GNAME.com website (By default, all IPs can access the API).

Configuration:

GNAME_APPID (API applications created in Reseller > API Settings)
GNAME_APPKEY
Tested with:
acme.sh v3.x
Domains: aikugou.com, multiple other domains
Tested by ShellCkeck and shfmt

[github-actions]

Welcome
READ ME !!!!!
Read me !!!!!!
First thing: don't send PR to the master branch, please send to the dev branch instead.
Please read the DNS API Dev Guide.
You MUST pass the DNS-API-Test.
Then reply on this message, otherwise, your code will not be reviewed or merged.
Please also make sure to add/update the usage here: https://github.com/acmesh-official/acme.sh/wiki/dnsapi2
注意: 必须通过了 DNS-API-Test 才会被 review. 无论是修改, 还是新加的 dns api, 都必须确保通过这个测试.

[GNDevProd]

We have completed all the tests. Is there anything else we need to do to proceed with the PR application

[neilpang]

@copilot review this pr

[GNDevProd]

update use _head_n