feat: Support INTERVAL type (#219)

* Bump cloud.google.com/go/spanner to v1.80.0

* Support INTERVAL type

* Fix typo

DisableNativeMetrics: true to spanner.Client (#207)

* add --disable-native-metrics flag

* Revert "add --disable-native-metrics flag"

This reverts commit 5051f79.

* DisableNativeMetrics: true

Add transaction-level isolation level setting (#206)

Enables optionally setting the isolation level at a transaction-level to either `SERIALIZABLE` or `REPEATABLE READ`. If the isolation level is not set, Spanner will default to `SERIALIZABLE` isolation.

Update google-cloud-go/spanner to v1.77.0 (#204)

* Update google-cloud-go/spanner to v1.77.0

* Update go version for github action to 1.23

* go mod tidy

Add cli flag `--version` to show version of spanner-cli (#198)

Implement --proto-descriptor-file (#195)

* Implement --proto-descriptor-file

* Update README.md

* Fix UseStatement with --proto-descriptor-file

* Do go mod tidy

* Add comments

* Update a comment

* go mod tidy with Go 1.19.13

* Fix to reflect review comment

* Fix variable name

Add CLI flag `--skip-tls-verify` (#194)

* Add CLI flag `--skip-tls-verify`

* Update README for `--skip-tls-verify`

Add typename in header and add DESCRIBE statement (#191)

* Add typename into header

* Implements DESCRIBE statement

* Fix column name in DESCRIBE

* Update tests

* Unify ExplainDmlStatement into ExplainStatement

* Add IsMutation in ExplainStatement

* Fix AffectedRows

* Improve EXPLAIN in Cloud Spanner Emulator

* Add comment

* Rename field name

* Fix PROTO typename

* Fix integration_test.go

* Update README.md

* Separate ExplainStatement and DescribeStatement

* Implement formatTypeSimple

* Refactor printResult

* Support typename in header of DML

* Use raw []*pb.StructType_Field

* Implement extractColumnNames() to extract column names

* Revert signature of parseQueryResult()

* Fix AffectedRows

Support PROTO, ENUM (#182)

* Support PROTOs

* add comment

* add testdata

* Fix typo

* Use non-deprecated package

* Change function order

* Use Enum() in test

* Add TestDecodeColumnProto and TestDecodeColumnProtoArray

* Rewrite TestDecodeColumnProto and TestDecodeColumnProtoArray

* Some cleanup

* Tidy imports

* Replace PROTO tests to TestDecodeColumnGCV

* Add comments

* Fix test case

* Remove testdata/protos

* Update comments

* Reorder test cases

* Remove useless use of NullProtoEnum

Support GRAPH statement (#181)