Allow running multiple namespaces in a session

[ankatiyar]

Description

Follow up from #4507 and part of #4506

Context

Noted by multiple team members in #4507 as desired behaviour.
#4507 (comment) @merelcht
#4507 (comment) @Huongg
#4507 (comment) @ElenaKhaustova

Allow users to run multiple namespaces

Possible Implementation

Make --namespace behave like --nodes

kedro/kedro/framework/cli/project.py

Lines 153 to 161 in 36b01b2

	@click.option(
	"--nodes",
	"-n",
	"node_names",
	type=str,
	default="",
	help=NODE_ARG_HELP,
	callback=split_node_names,
	)

NOTE:

• This would be breaking since we would likely have to rename --namespace to --namespaces which might be not a big deal since Kedro 1.0.0 is in the works (see Investigate CLI inconsistencies  #2014 where we pluralised flags that accepted multiple values)

Possible Alternatives

Use click's multiple option: https://click.palletsprojects.com/en/stable/options/#multiple-options, which would allow us to do kedro run --namespace=namespace1 --namespace=namespace2