Java: Add more neutrals and improve java.net.URL models

[atorralba]

Adds more neutral models to help the model generator ignore certain callables.

This is similar to #15906, in the sense that it adds neutral models to prevent the model generator from generating summaries for them. These models were spotted while evaluating #14919.

Also, this PR improves the precision of certain URL models by using synthetic fields so that the parts of a URL are tainted separately. The reasoning is:

• Control over the host: full URL object tainted.
• Control over the path, query, and/or fragment: synthetic field path tainted.
• Control over the protocol or port: no taint.

[github-actions]

⚠️ The head of this PR and the base branch were compared for differences in the framework coverage reports. The generated reports are available in the artifacts of this workflow run. The differences will be picked up by the nightly job after the PR gets merged.

Click to show differences in coverage

java

Generated file changes for java

• Changes to framework-coverage-java.rst:

-    Java Standard Library,``java.*``,10,746,239,80,,9,,,25
+    Java Standard Library,``java.*``,10,760,240,80,,9,,,26
-    Totals,,308,18962,2559,338,16,128,33,1,409
+    Totals,,308,18976,2560,338,16,128,33,1,410

• Changes to framework-coverage-java.csv:

- java.net,22,3,24,,,,1,1,,,,,,,,,,,,,,,,,,,,,,,,,,,,20,,,,,,,,,,,,,3,24,
+ java.net,23,3,31,,,,1,1,,,,,,,,,,,,,,,,,,,,,,,,,,,,21,,,,,,,,,,,,,3,31,
- java.security,21,,,,,11,10,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
+ java.security,21,,7,,,11,10,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,3,4