[TRIS-722] Custom Tagging

[RikishK]

Options to add custom tags are in the order:

environment variable dictionary,
step functions cli create flag,
batch decorator variable dictionary

This PR builds ontop of this PR: #1628 - this original PR did not work when testing but I would like to credit it here as some of the changes are still used.

[RikishK]

Testing

Setup:

Environment variable:

{ name: 'METAFLOW_BATCH_EMIT_TAGS', value: 'True' },
{ name: 'METAFLOW_BATCH_DEFAULT_TAGS', value: '{"default_greeting": "default_world"}' }

Step functions create command:

step-functions create --aws-tags "hello=world"

Flow:

from metaflow import (
    FlowSpec,
    step,
    batch,
    retry,
    schedule,
    project,
    conda,
    current
)
import logging
import logging_setup

logging_setup.configure()


custom_step_tags = {
    "goodbye": "world",
    "hello": "universe",
   #"inv@lid": "t@g"
    }

@project(name="ml_apac_trisolaris")
@schedule(hourly=True)
class CanarySimpleAdhoc(FlowSpec):
    @step
    def start(self):
        self.logger = logging.getLogger(self.__class__.__name__)
        self.logger.info(f"Canary Hello")
        self.next(self.hello)

    @batch(cpu=1, memory=500, tags=custom_step_tags)
    @retry
    @step
    def hello(self):
        self.logger.info("Canary Hello World in Batch!")
        self.next(self.end)

    @step
    def end(self):
        self.logger.info("HelloAWS is finished.")


if __name__ == "__main__":
    CanarySimpleAdhoc()

Output/Result:

Start step batch tags:

Hello step batch tags:

Additional notes:
Tag validation was tested with "inv@lid": "t@g" which caused an error as expected.