Make Polaris safe against certain unparseable locations

[snazy]

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.