Enable doclint

[mstahv]

Doclint is currently disabled in the flow-component-base and we thus end up with a lot of broken JavaDocs in our component documentation.

Don't know why it is disabled originally, might be because we automatically generate broken JavaDocs (see e.g. vaadin/vaadin-text-field-flow#123 ), apparently from our web component docs.

We should turn doclint on, disable it in projects that has broken docs and preferrably fix docs one by one.

[denis-anisimov]

I'm not sure but it might be that doclint has been disabled by me because it was not possible to release components.
I don't recall the exact error but I believe there had been some mistakes in some javadocs (and it wasn't easy to fix those mistakes may be because they are generated) and as a result javadoc artifact hasn't been published. That prevented a component release.
So when you enable doclint please make sure that javadoc artifact may be generated and published.

[denis-anisimov]

It may be bug may be enhancement.

It doesn't break any functionality but the javadocs generated for our component may be not really valid and slightly broken.

The reason (I think) is the autogenerated javadocs . And it may be not that easy to fix this.