[FEAT] Handle all up flags as role variables

[artis3n]

We're up to 3 or so exceptions to tailscale_args, where some flags are handled by dedicated variables in this role and most are not. This is confusing behavior. Originally, tailscale_args was set up this way because the Tailscale CLI was new and undergoing rapid development and there wasn't a guarantee that flags would be stable. This is no longer the case, and supporting all flags as arguments to this role would simplify usage and "Ansible-ize" the rest of the parameters.

Edit July 2024, starting on this:

Please comment on this issue and get sign-off from @artis3n before making PRs for any of these flags. I have an idea how I want this to work and I welcome contributions for it, but I don't want you to waste effort!

Flags that will become input variables to this role:

• --accept-dns. Possible values: true/false
• --accept-risk. Possible values: "lose-ssh", "all", or ""
• --advertise-exit-node. Possible values: true/false
• --advertise-routes. Values will be a list<string> and each input will be validated as valid CIDR syntax.
• --advertise-tags. Values will be a list<string>.
• --authkey. Already a dedicated variable.
• --exit-node. Value will be a string, and can be an empty string to disable a previously set configuration.
• --exit-node-allow-lan-access. Possible values: true/false
• --force-reauth. Possible values: true/false
• --hostname. Value will be a string.
• --login-server. Value will be a string.
• --netfilter-mode. Possible values: "off", "nodivert", "on".
• --operator. Value will be a string. Value must be an existing Linux user on the target, or the role will fail.
• --qr. Won't be supported by this role.
• --reset. Possible values: true/false
• --shields-up. Possible values: true/false
• --snat-subnet-routes. Possible values: true/false
• --stateful-filtering. Possible values: true/false
• --ssh. Possible values: true/false
• --timeout. Value will be an integer representing time in seconds.
• --unattended. Windows-only, so won't be supported by this role.

[artis3n]

Going to start thinking about this more actively. Collected current list of flags from https://tailscale.com/kb/1241/tailscale-up in the description.