[DOC-2558] docs(GSQLAPI): Add authentication header for GSQL example request;

[ArthurXie-tg]

https://graphsql.atlassian.net/browse/DOC-2558

1. Emphasised 3 auth approaches at the begin of the doc page
2. Add authentication header to example requests (mix of user-password and jwt-token)

[victorleeTG]

@ArthurXie-tg The page https://docs.tigergraph.com/tigergraph-server/4.1/api/ already explains the authentication requirement/header.
Users should think and want to think of all endpoints as one group; not GSQL endpoints and other endpoints. The rules for endpoints should as uniform as possible and presented in one general "API" page. Of course, we should also have a link from the GSQL endpoints page pointing to the general point.

I recommend that you

1. review the rules on this page to see if they are correct.
2. add a sentence on the GSQL endpoints page advising them where to look for authentication information.

I have one question:
It is not clear in the examples why you sometimes use username/password and sometimes use a token? It is random, or is there a pattern?

I personally do not like to show -u tigergraph:tigergraph in every example. It is not really a good practice. I would have a note in the Authentication section telling them that this is the default username/password. It should ONLY be user for a private personal deployment where you are not concerned about security. We tell users that they really should change the password, for security reasons.

[dadongwang-tg]

1. let's change to use in all examples @ArthurXie-tg
2. for GSQL API there is 3 authentication methods, while for RESTPP API, there is only one authentication method, let's state this as well