[HttpBasicAuth] Use positive isBasicBasic tag instead of negative isBasicBearer

Created by: sebastien-rosset

For HTTP basic auth, many mustache templates use a convention to negate the isBasicBearer tag, i.e. the case for HTTP basic auth is the negation of isBasicBearer. The problem is this only works when there are two possible HTTP auth, 1) basic auth and 2) bearer token. To support more http auth methods, we should stop using the negation of "isBasicBearer".

...
{{^isBasicBearer}}
   // do stuff for HTTP basic authentication
{{/isBasicBearer}}
{{#isBasicBearer}}
   // do stuff for bearer authentication
{{/isBasicBearer}}
....

I am proposing that instead, we change the templates as follows:

{{#isBasicBasic}}
   // do stuff for HTTP basic authentication
{{/isBasicBasic}}
{{#isBasicBearer}}
   // do stuff for bearer authentication
{{/isBasicBearer}}
....

I started making the change for Javascript. If that seems a reasonable change to reviewers, I can make the change everywhere.

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