Add plugin version check to Kibana startup

[simianhacker]

The nature of this issue has changed. See here for updated description

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See discussion of pros and cons #6532

[BigFunger]

Currently the plugin installer does a version check to make sure that the plugin being installed is compatible with the installation of Kibana.

After #8222, this will include functionality that allows the plugin author to explicitly specify which version of Kibana the plugin is compatible with regardless of the plugin version.

The problem is that if the user successfully installs plugins (with the version check passing) and then updates to a new version of Kibana, they have successfully put Kibana in a state where there are incompatible plugins installed.

To fix this, we need to add a check during the start-up process of kibana while plugins are being initialized that checks to see if the plugin's Kibana version still matches the currently installed Kibana version. If it does not, the following should happen:

1. The user should be presented with a warning message in the console.
2. The plugin should be disabled.