eslint-plugin: Increase severity of JSDoc rules to error

[aduth]

Previously: #16869 (comment)

We should generally seek to avoid any 'warn' severity in our rulesets. If we have a rule, it should be enforced strictly, else it shouldn't be a rule. Exceptions are to be made using inline comments.

Task: In the jsdoc ruleset, all custom rule configurations should be changed from 'warn' to 'error'. Similarly, if we are extending 'plugin:jsdoc/recommended', we should override all rules with equivalents where the severity is changed from 'warn' to 'error'.

Reference for 'jsdoc/recommended' rules: https://github.com/gajus/eslint-plugin-jsdoc/blob/master/src/index.js#L34

[gziolo]

We should generally seek to avoid any 'warn' severity in our rulesets. If we have a rule, it should be enforced strictly, else it shouldn't be a rule. Exceptions are to be made using inline comments.

Totally agree. Warnings are ignored by contributors. We should stop using them and pick errors instead 👍

[aduth]

Noting that we have a fair few warnings related to invalid syntax caused by TypeScript-specific JSDoc extensions which are not yet supported by eslint-plugin-jsdoc.

See also: jsdoctypeparser/jsdoctypeparser#50, #18838

We could consider to either leave this one specifically as a warning in the meantime (granting that it's blocked by some future compatibility improvements), or disable it altogether.