Advisors: Display checks filtered by category

The problem:

Currently, the view in PMM that displays the list of available checks render all checks at once. As this list will grow, it will be cumbersome to make some sense of it, and to find particular checks.

The solution:

Introduce filtering. Long term, we will provide several different options to filter the list, with the possibility to combine different criteria. In the scope of this user story, we will implement the very first filter that will allow users to narrow down the list of checks by category.

User story:
As a user, I want to be able to filter the list of checks by category (e.g. security, performance, configuration, etc.) so that I can narrow down the list of checks to something more meaningful to me at any time.

The category field present in all check files can be seen below:

checks:
  - version: 2
    name: postgresql_check
    summary: PostgreSQL awesome check
    description: Checks something important
    tiers: [ anonymous, registered ]
    interval: standard
    family: postgresql
    category: configuration                       // <------ 
    queries: ...
    script: ...

The category attribute should also be available to the frontend so that it can be used to filter the list of checks and check results, e.g "give me all performance checks", "give me all security, and configuration checks, only", etc.

UI/UX:

Acceptance criteria:

• **I expect to be able to see the list of categories on the view that renders the list of checks, and I expect to be able to select one or multiple categories
• After selecting one or multiple categories, I expect the list of checks to automatically refresh to render the list of checks that match the selected categories
• I expect to be able to have an action to remove the filter (i.e. the selected categories). After removing the filter, I expect to see the whole list of checks