AMBARI-23201 Integrate ViewService with Swagger

[g-boros]

What changes were proposed in this pull request?

Add swagger documentation to View API endpoints

How was this patch tested?

Generate swagger docs by

test -Drat.skip -Dcheckstyle.skip -DskipTests -Dgenerate.swagger.resources

then manually checking Swagger output at ambari-server/docs/api/generated/index.html

checkstyle using:

clean checkstyle:checkstyle -pl ambari-server

API endpoint calls at api/v1/alert_targets have also been tested manually

please review @Jetly-Jaimin @adoroszlai @benyoka

[asfgit]

Refer to this link for build results (access rights to CI server needed):
https://builds.apache.org/job/Ambari-Github-PullRequest-Builder/1236/
Test PASSed.

[adoroszlai]

Naming of property constants is not consistent. In some classes qualified properties (.../...) have plain names (eg. VIEW_NAME = VIEW_INSTANCE_INFO + PropertyHelper.EXTERNAL_PATH_SEP + VIEW_NAME_PROPERTY_ID), while in others they have complex names (eg. VIEW_VERSION_INFO_VIEW_NAME_PROPERTY_ID = VIEW_VERSION_INFO + PropertyHelper.EXTERNAL_PATH_SEP + VIEW_NAME_PROPERTY_ID). I'm fine with either type, but would be nice if we could keep/make them consistent.

[adoroszlai]

Odd whitespace

[g-boros]

fixed property constant naming in 3516b29

All plain names are called like XX_PROPERTY_ID if value is "XX", like:

public static final String ICON_PATH_PROPERTY_ID = "icon_path";

Qualified properties use short name, like:

public static final String ICON_PATH = VIEW_INSTANCE_INFO + PropertyHelper.EXTERNAL_PATH_SEP + ICON_PATH_PROPERTY_ID;

@adoroszlai, @benyoka please have a look for review, thanks

[asfgit]

Refer to this link for build results (access rights to CI server needed):
https://builds.apache.org/job/Ambari-Github-PullRequest-Builder/1278/
Test FAILed.
Test FAILured.