Do not show nodes if user does not have access to them

[klizhentas]

Description

Teleport RBAC can prohibit access to nodes by label, however tsh ls still shows them. Exclude the nodes that user does not have access to by filtering out those nodes in

auth_with_roles.go and applying RBAC attempt to every node in the list.

Expected outcome

tsh ls and UI and any API should not show nodes if user is denied access to them.

Some details

Teleport roles allow to connect as certain user but not another, make sure the node is not shown if user is not allowed to connect as any user.

[aberoham]

Related ask from a Teleport Enterprise customer, see #1862 ("hide Login As button if role lacks login permissions")