smb: make timeout and num contexts menu options

[cscd98]

Guidelines

1. Rebase before opening a pull request
2. If you are sending several unrelated fixes or features, use a branch and a separate pull request for each
3. If possible try squashing everything in a single commit. This is particularly beneficial in the case of feature merges since it allows easy bisecting when a problem arises

Description

1. Makes timeout and connections configurable
2. Hardens picking the right context
3. Makes auth mode a unsigned

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