fix(ui/QTable): Use correct definition for @request's filter

[yusufkandemir]

What kind of change does this PR introduce?

• Bugfix
• Documentation

Does this PR introduce a breaking change?

• No

Anyone who was misled by the API docs(code examples were correct) and has passed a function instead of a string/object should be warned. Their code will still work since they can send a function filter to requestServerInteraction and expect the function they've sent in onRequest and use it as they wish, but we should advise against this. That is because if they don't pass in a function when calling requestServerInteraction or QTable triggers @request itself, they will receive QTable's filter prop, which can be string/object/undefined.

The PR fulfills these requirements:

• It's submitted to the dev branch (or v[X] branch)
• Any necessary documentation has been added or updated in the docs or explained in the PR's description.

Other information:

In the past, I have made some investigations about the type and had a discussion with @rstoenescu:
ab3708d (#11347)

But, yesterday, someone from the community posted this problem. After some investigation and discussion today, I am pretty confident that JSON API and docs examples are wrong. I created this PR to fix&clarify this problem.

@metalsadman also tagging you here since we had a brief discussion about this on our Discord server.

[engineertdog]

Thanks for the PR, Yusuf. One comment though.

tableRef.value.requestServerInteraction should be the following instead, because tableRef can be undefined.

tableRef.value?.requestServerInteraction

[yusufkandemir]

@engineertdog that's not entirely correct. You wouldn't be able to trigger server interaction and always have an empty table otherwise. tableRef will always be defined in the onMounted hook and anywhere that gets called everything is settled. That's how template refs work. It would only be undefined if you didn't return it(which would be a bigger mistake) or you have v-if that evaluates to false on the q-table. So, in this example, it will always be undefined, so it's correct.