The previous implementation combined --mount and -v notation
of argument [1] adding :ro to make the read-only mount point.
E.g. the command [2] called docker with the following
params: [3]. As a result instead of the read-only
folder /tmp/source, the read-write folder /tmp/source/:ro/'
is created.
This PR:
1. substitutes ':ro' with correct ',readonly'.
2. changes 'src=' and 'dst=' with 'source=' and 'target=' as
it is stated in the documentation [1]
3. introduces the ability to EXPLICITLY create a mountpoint
with read-write access. To do so it's necessary to add
',rw=true' to the --mount argument
4. corrects UTs adds some additional coverage for added
functionality
[1]
https://docs.docker.com/storage/bind-mounts/#use-a-read-only-bind-mount
[2]
kustomize fn run ./d --mount type=bind,src=$(pwd)/test/,dst=/tmp/source/
[3]
--mount type=bind,src=/home/ubuntu/kpt-functions-catalog/functions/ts/test/,dst=/tmp/source/:ro
