File upload missing in homepage

[m-adams]

Kibana version: 7.11.1

**Elasticsearch version:**7.11.1

**Server OS version:**ESS

Browser version: Chrome

Browser OS version: Mac

Original install method (e.g. download page, yum, from source, etc.): ESS

Describe the bug:

When I launch Kibana, sometimes, but not every time, the "File Upload" link is missing from the homepage.
No obvious errors in the console and that item is missing from the DOM

Steps to reproduce:

1. Hard to reproduce, launch Kibana multiple times

Expected behavior:

The File Upload link should be there

Screenshots (if relevant):

Errors in browser console (if relevant):

No

Provide logs and/or server output (if relevant):

Any additional context:

[elasticmachine]

Pinging @elastic/kibana-core (Team:Core)

[lukeelmers]

@nreese Any thoughts as to whether this is possibly related to the recent file upload refactoring?

[nreese]

Probably not, since the first file upload refactoring work did land until 7.12 - #89640

[pgayvallet]

The upload file action is registered by the ml plugin. However ml waits for the license to be fetched to ensure that it should register the action

kibana/x-pack/plugins/ml/public/plugin.ts

Lines 140 to 148 in 6ef7d2c

	licensing.subscribe(async (license) => {
	const [coreStart] = await core.getStartServices();
	const { capabilities } = coreStart.application;
	if (isMlEnabled(license)) {
	// add ML to home page
	if (pluginsSetup.home) {
	registerFeature(pluginsSetup.home);
	}

This causes a race condition, as we may render the home page before the license is effectively resolved on the client side.

cc @elastic/ml-ui

I guess one possible solution would be to change the API of the FeatureCatalogueRegistry of the home plugin to expose an observable, but that represents some work and is also quite in opposition to the 'register things only during setup' logic.

[jgowdyelastic]

This is similar to how we register our sample dataset links which we only do after a license check.

These also suffer from a user permissions check issue where a user with no permission to create ML jobs or even no permission to access ML can still see and click the link.

[jgowdyelastic]

This should be fixed by #101393
The file upload link is now registered by the new file data visualizer plugin and is not dependent on a license check