Context

This MR applies the Alcotezt wrapper on the tests:

Practically, this MR contains:

Modification manifest/main.ml for using tezt instead of tests registration function and generate dune and opam files.
Modifying the tests to make it compile with Alcotezt

Manually testing the MR

Running the test (example for src/proto_015_PtLimaPt/lib_protocol/test/integration/gas)

dune exec src/proto_015_PtLimaPt/lib_protocol/test/integration/gas/main.exe -- --info

Document the interface of any function added or modified (see the coding guidelines)
Document any change to the user interface, including configuration parameters (see node configuration)
Provide automatic testing (see the testing guide).
For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
Select suitable reviewers using the Reviewers field below.
Select as Assignee the next person who should take action on that MR