…#1)

Initial read-only Snowflake Catalog implementation built on top of the Snowflake JDBC driver,
providing support for basic listing of namespaces, listing of tables, and loading/reads of tables.

Auth options are passthrough to the JDBC driver.

Co-authored-by: Maninder Parmar <maninder.parmar@snowflake.com>
Co-authored-by: Maninder Parmar <maninder.parmar+oss@snowflake.com>
Co-authored-by: Dennis Huo <dennis.huo+oss@snowflake.com>

Add JdbcSnowflakeClientTest using mocks; provides full coverage of JdbcSnowflakeClient
and entities' ResultSetHandler logic.

Also update target Spark runtime versions to be included.

consistency and future interoperability with inheriting from abstact
unittest base classes.

-Convert unittests to all use assertj/Assertions for "fluent assertions"
-Refactor test injection into overloaded initialize() method
-Add test cases for close() propagation
-Use CloseableGroup.

…seLocation

SnowflakTableOperations class itself, add test case.

SnowflakeClient/JdbcSnowflakeClient layers and merge SnowflakeTable
and SnowflakeSchema into a single SnowflakeIdentifier that also
encompasses ROOT and DATABASE level identifiers.

A SnowflakeIdentifier thus functions like a type-checked/constrained
Iceberg TableIdentifier, and eliminates any tight coupling between
a SnowflakeClient and Catalog business logic.

Parsing of Namespace numerical levels into a SnowflakeIdentifier
is now fully encapsulated in NamespaceHelpers so that callsites
don't duplicate namespace-handling/validation logic.

…ssert

in favor of assertj's Assertions.

…ileIO into core

with its own unittest.

exist.

Refactor for naming conventions and consolidating identifier
handling into NamespaceHandlers.

Make FileIO instantiated fresh for each newTableOps call.

any use of commons-dbutils; refactor ResultSet handling fully into
JdbcSnowflakeClient.java.

…TableOperations.java

Co-authored-by: Eduard Tudenhöfner <etudenhoefner@gmail.com>

…exceptions,

private members if not accessed outside, move precondition checks, add test for
NamespaceHelpers.

…lity.

…tial