Add snowflake support

[dmitchell]

I'd really like access to the slack channel or to some other means to communicate w you re how to integrate snowflake; however, of course, I don't have a jetbrains email address and the slack channel requires one.

Before then, this is a trivial edit (fixing task name and formatting).

Problems I'm having w writing the new dialect

• snowflake is always hosted in the cloud by snowflake (PAAS); so, cannot create a localhost docker container for it. Right now I have it creating an empty container. Any idea how to intelligently set this up?
• snowflake does not support indexes (it's a column oriented db). Any suggestions how to properly encode?
• snowflake does not have several types such as byte. Any suggestions how to integrate so that bytes cast to int?
• snowflake does not support NOW() but does support CURRENT_TIMESTAMP(). afaict, there's no way to police that other than hardcoding the few places the current tests call NOW().

[Tapac]

@dmitchell , I had sent you the invitation for kotlinlang slack. Check your gmail for it.

[Tapac]

snowflake is always hosted in the cloud by snowflake (PAAS)....

Maybe it's possible to set up free/trial instance of Snowflake and use it in tests?

snowflake does not support indexes...

Just throw UnsupportedByDialectException from DatabaseDialect.create/dropIndex functions.

snowflake does not have several types such as byte.

Define the most suitable type (line integer) and check that corresponding ColumnType have conversion from/to it.

snowflake does not support NOW() but does support CURRENT_TIMESTAMP()

There is CurrentDateTime function which uses CURRENT_TIMESTAMP by default.