Dataset.from_images should not add slashes in layer names

[normanrz]

Context

• Affected library: e.g. webknossos

Some datasets are imported with subfolders. The layer names should not contain slashes. It should be enforced that layers can only have valid names. Ask @fm3 for the regex.

[fm3]

context: https://scm.slack.com/archives/C02Q35Q28P5/p1686662646064909

webknossos does not currently enforce any layer name rules, except for the minimum-one-character rule. slashes are definitely a problem, though, as they have special meaning in file system and uri context

[fm3]

Now annotation layers on the other hand are checked in postgres as name VARCHAR(256) NOT NULL CHECK (name ~* '^[A-Za-z0-9\-_\.]+$'), – but that would be too strict for all dataset layers, I think voxelytics for example uses $ signs