[SPARK-20239][CORE] Improve HistoryServer's ACL mechanism

## What changes were proposed in this pull request?

Current SHS (Spark History Server) two different ACLs:

* ACL of base URL, it is controlled by "spark.acls.enabled" or "spark.ui.acls.enabled", and with this enabled, only user configured with "spark.admin.acls" (or group) or "spark.ui.view.acls" (or group), or the user who started SHS could list all the applications, otherwise none of them can be listed. This will also affect REST APIs which listing the summary of all apps and one app.
* Per application ACL. This is controlled by "spark.history.ui.acls.enabled". With this enabled only history admin user and user/group who ran this app can access the details of this app.

With this two ACLs, we may encounter several unexpected behaviors:

1. if base URL's ACL (`spark.acls.enable`) is enabled but user A has no view permission. User "A" cannot see the app list but could still access details of it's own app.
2. if ACLs of base URL (`spark.acls.enable`) is disabled, then user "A" could download any application's event log, even it is not run by user "A".
3. The changes of Live UI's ACL will affect History UI's ACL which share the same conf file.

The unexpected behaviors is mainly because we have two different ACLs, ideally we should have only one to manage all.

So to improve SHS's ACL mechanism, here in this PR proposed to:

1. Disable "spark.acls.enable" and only use "spark.history.ui.acls.enable" for history server.
2. Check permission for event-log download REST API.

With this PR:

1. Admin user could see/download the list of all applications, as well as application details.
2. Normal user could see the list of all applications, but can only download and check the details of applications accessible to him.

## How was this patch tested?

New UTs are added, also verified in real cluster.

CC tgravescs vanzin please help to review, this PR changes the semantics you did previously. Thanks a lot.

Author: jerryshao <sshao@hortonworks.com>

Closes #17582 from jerryshao/SPARK-20239.