HPCC-11166 Separate Validate Package page to two, etc

Separate Validate Package Map page to two pages, one for validating
active package map and one for validating any package content.
Change the page layout for better display. When validating active
package map, the page will display the content of the active
package map. The content can be revised and validated. A save button
will be added in another pull request. In Validate Package Content
page, a upload button is added to allow a user to load package
content from a file. A user may also drag/drop a package file or
copy package content into the page.

Revised based on code review.

Signed-off-by: Kevin Wang kevin.wang@lexisnexis.com