fix: a relative path in `mason.yaml will` result in an absolute path in `mason-lock.json`

**Description**

When adding a brick with a relative path to mason.yaml, the mason-lock.json will contain an absolute path to it

**Steps To Reproduce**

mason new sample -o bricks
mason add sample --path bricks/sample

**Expected Behavior**

`mason-lock.json` should contain `bricks/sample`, but instead contains the full absolute path