plain text for credential

[billmoling]

Issue description

In this https://github.com/apache/apisix-dashboard/blob/master/api/conf/conf.yaml line 78 -81 the dashboard authentication use plain text in the configuration. it would cause the security risk for auditing is there any way to fix?

Expected behavior

NO plain test for cred

How to Reproduce

NA

Screenshots

No response

Environment

• apisix version (cmd: apisix version):
• OS (cmd: uname -a):
• OpenResty / Nginx version (cmd: nginx -V or openresty -V):
• etcd version, if have (cmd: run etcd --version):
• apisix-dashboard version, if have:
• Browser version, if have:

Additional context

No response