Snowddl

- `SHOW PROCEDURES` was replaced with `SHOW USER PROCEDURES`, in line with Snowflake release notes.
- Added `owner_schema_read`, `owner_schema_write` parameters for schema. If specified, grants READ or WRITE roles from other schemas to the OWNER role of the current schema. It helps to make objects in other schemas accessible for `VIEWS` and `PROCEDURES`. Normally OWNER role can only access objects in the current schema.
- Dependency management was enabled for schema roles.

- MD5 markers which are automatically generated for `STAGE FILES` are now uploaded directly using `file_stream` option for `.execute()` command of Snowflake Python Connector. Temporary directory is no longer used.
- `file_stream` option is now available for `.execute_safe_ddl()`, `.execute_unsafe_ddl()`. It might be used in future for more advanced operations with contents of internal stages.

- Added technical placeholder `env_prefix` which is always available for YAML configs. It should be used to access objects in other databases when specifying `VIEW` definitions (`${{ env_prefix }}db_name.schema_name.object_name`). Objects in the same database can still be accessed without specifying database name (`schema_name.object_name`).
- Fetching list of existing `STAGE FILES` no longer fails if stage exists in blueprints, but does not exist in Snowflake account.
- Resolver for `STAGE FILES` is now skipped when "destroy" action is being called. All files are destroyed automatically when stage is deleted.

- Replaced explicit `format_exc()` calls during config validation with modern `TracebackException.from_exception().format()` API. Pre-formatted error messages will no longer be stored in `SnowDDLConfig`, but rather be formatted on demand using `Exception` object only.
- Fixed typos in some JSON schemas.
- Simplified the way how `.resolved_objects` property is being stored for resolvers. Now it is a basic `dict` with object full name as key and `ResolveResult` enum as value.

- Added more tests for `TABLE` and `VIEW` object types.
- Improved project description.

- Implemented `EXTERNAL FUNCTION` object type.
- Added validation for YAML config file names for object types supporting overloading.
- Re-create "invalid" `EXTERNAL TABLES` automatically.
- Switched test account to AWS.