Implement base linear algebra methods for CPU and GPU

[henrique-borba]

• [x] matmul
• [x] inv
• [x] det
• [x] dot
• [x] inner
• [x] outer
• [x] eig
• [x] cond
• [x] cholesky
• [x] solve
• [x] svd
• [x] trace
• [x] qr
• [x] norm
• [x] LU
• [x] lstsq