NNS1-3139: Add maturity column in projects table

[dskloetd]

Motivation

We want to make it easy to see all the maturity on all projects by adding a column to the staking projects table.

Changes

1. Add ProjectMaturityCell component which renders either -/- of there is no data, the maturity if there is data, or nothing if the user doesn't have neurons for that project.
2. Use the cell component to add a column in the ProjectsTable.

Tests

1. Page objects and unit tests added.
2. Manually at https://qsgjb-riaaa-aaaaa-aaaga-cai.dskloet-ingress.devenv.dfinity.network/staking/

Todos

• [ ] Add entry to changelog (if necessary). We haven't done a release yet since the projects table was enabled so that entry covers this as well.