added sys.use_token, swaps between tokens and can revert to self with id 0

[KS-7250]

What type of PR is this?

/kind feature
/kind eldritch-function

What this PR does / why we need it:

We now have a global token store, but no way to swap between tokens in that store. sys.use_token() fixes that

• sys.use_token(id: int) -> bool

$> sys.tokens()

| active | id | source               |
| ------ | -- | -------------------- |
| False  | 0  | process_token        |
| True   | 1  | impersonate:pid:6767 |

$> sys.shell('whoami')['stdout']
nt authority\system

$> sys.use_token(0)                   # revert to process token
True

$> sys.tokens()

| active | id | source               |
| ------ | -- | -------------------- |
| True   | 0  | process_token        |
| False  | 1  | impersonate:pid:6767 |

$> sys.shell('whoami')['stdout']
administrator

Which issue(s) this PR fixes:

Fixes N/A