Make Polaris safe against certain unparseable locations

Using `java.net.URI` for paths/locations generated/used by Apache Iceberg is particularly unsafe.

Characters that are illegal in URI string representations are not escaped by Iceberg and lead to runtime exceptions when parsed for example by `java.net.URI.create(String)`.

Example: A legit column/partition-field name `"_foo_bar_"` will end "as is" in any path generated by Iceberg, leading to ` Caused by: java.lang.IllegalArgumentException: Illegal character in path at index ...`.

The safest approach to prevent this issue entirely is to have a dedicated class that deals with "unsafe encodings", maybe call it "StorageUri".

Mixing "unsafe" and "safe" encodings will cause errors.