[GEOT-7365] Problems with requesting Features from a WFS Version 2.0.0 and using a HTTP proxy

[roarbra]

Injecting HTTPClient into XSD handling to take advantage of any configuration set in WFSDataStore or proxy setting.

In addition made some changes to the exception's thrown, and the exception that is passed if fetching the schema fails.

Checklist

• I have read the contribution guidelines.
• I have sent a Contribution Licence Agreement (not required for small changes, e.g., fixing typos in documentation).
• First PR targets the main branch (backports managed later; ignore for branch specific issues).
• Avoid Java 9+ split packages.
• All the build checks are green (see automated QA checks).

For core and extension modules:

• New unit tests have been added covering the changes.
• Documentation has been updated (if change is visible to end users).
• There is an issue in GeoTools Jira (except for changes not visible to end users).
• Commit message(s) must be in the form [GEOT-XYZW] Title of the Jira ticket.
• Bug fixes and small new features are presented as a single commit.
• The commit targets a single objective (if multiple focuses cannot be avoided, each one is in its own commit, and has a separate ticket describing it).

[mprins]

LGTM

[aaime]

Looks good, just a question below.

[aaime]

Does this improve error reporting somehow?
Quoting from the previously used constructor javadoc:

Constructs a new runtime exception with the specified cause and a detail message of (cause==null ? null : cause.toString()) (which typically contains the class and detail message of cause). This constructor is useful for runtime exceptions that are little more than wrappers for other throwables.

[roarbra]

I have noticed that by using the first approach, and nesting in several try-catch, we will end up with the exception message: "[java.lang.RuntimeException] [java.io.IOException] [java.sql.SQLException] Couldn't open connection."
I think those class names in front are misleading. Especially when they are sent in a ServiceException.