add interfaces for client side statements

* create jdbc project

* added spanner-jdbc to versions

* add interfaces for client side statements

* changed prerequisiteStatements to examplePrequisiteStatements

* add generic connection interface

* changed to normal getter name

#5808)

add public jdbc interface for Cloud Spanner

…5813)

add util for parsing read-only staleness values

* add DirectExecuteResultSet

* readability: extracted numberOfParameters and firstParameterType to vars

* add ReplaceableForwardingResultSet

* fixed CR year

* added note for zero-based column indices + added vars for readability

* add StatementResultImpl

* added missing test cases for convenience methods

* add client side statement parser

* changed loops to a map lookup

* fixed spacing between variables and javadoc

* merge with spanner-jdbc

* changed lists to sets

…tion retries (#5876)

* add specific AbortedExceptions for failed tx retries

* updated CR year

…tions (#5881)

add base interface for unit of work on connections

…anner (#5877)

* add jdbc types and type mappings for Cloud Spanner

* update CR year

* changed name to getSpannerType

* simplified if statements and added curly braces to for loops

* add CredentialService

* updated CR year

* remove public visibility

* make getAppDefault overridable and mock this in the test

* removed 'internal' from private method name

* add error msg as constant

* removed custom httptransport

* add ConnectionOptions

* add SpannerPool

* removed auto-generated methods

* changed to get-and-check-for-null

get and check for null is more appropriate in this case, as we would
never want to return null from this method

* added documentation

* fixed wrong null check

* add jdbc types and type mappings for Cloud Spanner

* update CR year

* add jdbc ResultSet

* added null checks and javadoc and fixed formatting

* added missing checks for negative overflow and added test cases

* fixed camel case

* refactored if-statements into one, added actual check for toString

* removed formatter hints

* extracted to variable + added extra documentation

* add ConnectionImpl

* fix CR year

* moved DdlClient creation to separate method

* updated changed class reference

* add ReadWriteTransaction

* refactor inner classes to separate files

* included allowed state to error msg

* added javadoc to the COMMIT and RUN BATCH statements

* removed todo no longer needed in public repo

* add DmlBatch

* updated CR year

* add jdbc connection implementation

* update CR year

* add warnings for ClientInfo

…tation (#5911)

* add jdbc Statement and PreparedStatement implementation

* updated CR year

* return successful/failed ddl statements

* changed variable names from x to value

* added missing test cases

* add DdlBatch

* return successful/failed DDL statements

* extracted update count extraction to a separate method

* add parameter store for jdbc parameters

* add null check

* added additional test statements

* added tests for null values in array and null-array

* add JdbcDriver

* add jdbc DataSource implementation

* removed information from test connection url

* add JdbcDatabaseMetadata

* added implementation for getUserName

…#5931)

* fixes compile errors, missing test classes and test failures

* updated CR years

* change integration tests to use the Spanner IT test env

* add DDL integration tests

* add extra information on failure

* fix typo

* extract correct error code

* merge with spanner-jdbc

…ns and retries (#6003)

* add integration tests for transactions and retries

* add assertions that the values are actually written

…ipts (#5999)

* change integration tests to use the Spanner IT test env

* use util method from verifier for reading sql statements from file

* integration tests hat are executed purely using sql scripts

* fixed typo's and removed unnecessary test statement