Change invite messaging alert on personal namespace

What does this MR do and why?

Change invite messaging alert on personal namespace

- Personal namespaces have different handling when it comes
  to billing and upgrading. Hence, the usual wording doesn't
  fit well when in that context.

- Move closeToLimit calculation to parent component
  - Move the CLOSE_TO_LIMIT_COUNT constant to the constants file
  - We need information about being close to the limit in more places
    now so it makes sense to calculate it once and then just keep passing
    it down as a prop.

- refs:
  https://gitlab.com/gitlab-org/gitlab/-/issues/360017
  https://gitlab.com/gitlab-org/gitlab/-/issues/348694/
  https://gitlab.com/gitlab-org/gitlab/-/issues/360017#note_953539203

Screenshots or screen recordings

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. In rails console enable the experiment fully

   Feature.enable(:free_user_cap)

2. Visit your personal member pages such as http://localhost:3000/sfigueroa_2022-03-08/waste/-/project_members
3. Click the invite members button. -->

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #360017 Related to #348694