Fewer syntax modules for error-monad

Context

A common issue with the existing error-monad syntax module is that there is just too many of them and which one am i supposed to open anyway how do I even know why shouldnt i just open the top one then it seems simpler.

This MR addresses this issue. Specifically, it removes the Tzresult_syntax and Lwt_tzresult_syntax modules entirely. Instead, it moves the tz-specific functions of these modules (essentially fail and and*) into the non-tz-specific version. The function (rather than the module) carries a prefix.

Instead of

let open Lwt_tzresult_syntax in
… fail …

you write

let open Lwt_result_syntax in
… tzfail …

All polymorphic functions/operators are left untouched.

The simplest way to understand the impact on programmers is to look at the diff of the tutorial.

Manually testing the MR

Checklist

• 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, the Development Version section of CHANGES.md for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR