perf: Make oc_group_folders.options a VARCHAR(255)

[CarlSchwan]

Allow to query this column without on-disk temp table on MySQL

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[come-nc]

Will the value always fit?

[solracsf]

@come-nc, yes, as far as I understand it.

Reasoning: the column is typed array{separate-storage?: bool} and has only that single boolean key since it was introduced. createFolder is the sole writer. If someone adds enough option keys to exceed 255 later, strict mode (default since MySQL 5.7 / MariaDB 10.2.4) fails the insert loudly, so it forces a column widening rather than corrupting silently.