Add profile restriction field to "My Courses" dropdown

[Jeremy Hopkins]

For our new online instance we need to be able to restrict "My Courses" drop down to certain user types from a custom profile field.

In short the same user check we use elsewhere needs to be made available for the "my courses" drop down list.

This should be added below the setting "theme_adaptable | enablemysites"

[Manoj Solanki]

Fix #860 . New profile field check for restricting my sites menu.

→ <<cset d39de0e71482>>

[Manoj Solanki]

Fix #860 . Updated to use function that already exists for checking menu access for any custom profile field.

→ <<cset fd34deb1dd67>>