Specify subnetid and routetableid via cloud provider config

[mrIncompetent]

What this PR does / why we need it:
This is a fix for #39996 which is needed since 1.6

Changes introduced from 1.6 broke partially(LoadBalancer) the support for running the master components in a different environment (different aws account/on premise). This PR will add support for specifying the Subnet & RouteTable to use via the cloud provider config.

Release note:

AWS cloud provider: fix support running the master with a different AWS account or even on a different cloud provider than the nodes.

[k8s-reviewable]

This change is 

[k8s-ci-robot]

Hi @mrIncompetent. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with @k8s-bot ok to test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[sttts]

@k8s-bot ok to test

[justinsb]

LGTM

[justinsb]

/lgtm

[k8s-github-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: justinsb, mrIncompetent

Needs approval from an approver in each of these OWNERS Files:

• pkg/cloudprovider/providers/aws/OWNERS [justinsb]

You can indicate your approval by writing /approve in a comment
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[k8s-github-robot]

@k8s-bot test this [submit-queue is verifying that this PR is safe to merge]

[k8s-github-robot]

Automatic merge from submit-queue

[k8s-ci-robot]

@mrIncompetent: The following test(s) failed:

Test name	Commit	Details	Rerun command
Jenkins GCI GCE e2e	1c1f02f	link	@k8s-bot gci gce e2e test this

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository. I understand the commands that are listed here.

[k8s-cherrypick-bot]

Commit found in the "release-1.6" branch appears to be this PR. Removing the "cherrypick-candidate" label. If this is an error find help to get your PR picked.