Group/project members - improve parity between frontend and backend naming

Follow-up to !61524 (comment 578017235)

In the members code there are some naming discrepancies between the frontend and backend code. Furthermore the member type naming is confusing because they aren't really "member types" and rather "resource types".

Proposal

We will have to update a lot of code to make all of the naming match up so it will be split up into 3 steps. Here is a POC MR with all the required changes that will be split up into multiple MRs: !78746 (closed)

Step 1

• Split the constant MEMBER_TYPES into 4 separate constants:
  • export const RESOURCE_TYPE_MEMBER = 'member';
  • export const RESOURCE_TYPE_GROUP_LINK = 'groupLink';
  • export const RESOURCE_TYPE_INVITED_MEMBER = 'invitedMember';
  • export const RESOURCE_TYPE_ACCESS_REQUEST = 'accessRequest';
• Update all references to MEMBER_TYPES constant to use the new constants
• Update naming in group_members_app_data and project_members_app_data_json to match the naming in the constants above.

Step 2

• Updating component file names to match the new RESOURCE_TYPE_* names

Step 3

• Update component props and Vuex store actions/mutations to match the new RESOURCE_TYPE_* names