Add snowflake_put output

[mihaitodor]

For anyone who'd like to test this out, Snowflake allows you to create a 30-day free trial account here.

I'd like to add a bunch of lints to the config, but wasn't sure what's the best way to do that currently. I know I did it here, but not sure how to get to that when starting from service.NewConfigSpec().

TODO: Add lints for:

• upload_parallel_threads only allows values between 1 and 99 (see here)
• password / SSH private key are exclusive
• don't allow snowpipe to be set when in user/password auth mode

Note: This is part of #658.

[Jeffail]

@mihaitodor I've added blobl linting: e7ee59a, worth trying when you get a chance

[mihaitodor]

@Jeffail Thanks so much for adding the linting functionality! It's awesome, but I found it useful to also add a LintRule method for the ConfigSpec.

In terms of ergonomics, it might be handy to allow users to chain multiple LintRules, so then each of them is run and they can see each separate lint if there are multiple issues. The match I used works too, but they'll only get the first error it encounters. Guess it can be improved with a fancier blobalng query, but that's harder to maintain.

[Jeffail]

Nice, extra props for fixing the batch docs.