Feat: Bastion component

[jamesgibbons92]

Closes #6364

Summary:

• Adds a new component 'Bastion' which is a standalone component for deploying an ec2 bastion acting as a tunnel into VPC protected resources. This is functionally equivalent to the bastion created in the VPC component, but has some additional improvements and can support a non-sst vpc by passing in the required props.
• Adds a version number to sst tunnel which prompts the user to run sudo sst tunnel install again if the binary code changes, this is just a hardcoded version variable which needs to be bumped when changes are made.
• sst tunnel now supports multiple bastions in a stack, this is probably a very small use case - but previously the command would just use the last _tunnel it found in the stack.

SSM Support

The tunnel code has been extended to support session-manager port forwarding, this is more secure than ssh as it does not require any public facing server. https://aws.amazon.com/blogs/aws/new-port-forwarding-using-aws-system-manager-sessions-manager/

• By default the bastion will deploy in 'ssh' mode, similar to the existing bastion.
• Opt in to ssm by passing an arg into the component.
• The only caveat to this mode is that it requires the aws-cli session-manager-plugin to be installed on the client system.

Notes:

• The existing bastion behaviour in VPC component is unchanged. I left this untouched to reduce the risk of regression issues, this new component is more useful for people needing to tunnel into a non-sst vpc, or if they want to use the more secure ssm tunnel mechanism.

Test plan:

Vpc with bastion: true (regression test, ensure the new tunnel code is backwards compatible):

Vpc with Bastion component in SSH mode:

Vpc with Bastion component in SSM mode:

Vpc with Shared Bastion component:

SST Dev:

Tunnel needs upgrade:

SSM mode but session manager plugin not installed:

Todo:

• Test MacOS

[jamesgibbons92]

@vimtor circling back to this now,
apart from the merge conflicts, are there any other changes you think I should make to this pr to get it merged?