Add a new function to fix TODO keywords globally

[maikol-solis]

Hi!

(This is the same discussion on Discord, but I put it here if someone else wants to join in).

The function org-gtd-projects-fix-todo-keywords-for-project-at-point is supposed to be run for each project heading to make sure there's a NEXT item in the list.

However, I think it would be more useful if the function were applied over each subheading under the 'Project' heading. This allows us to normalize the TODOs on every project at once, instead of going to each project by hand.

In my case, after some days of work, I finish with projects that only have 'TODO' items, but I don't realize it until I start making my weekly review.

For example, if I have this file, I would notice that the first one is formed by only TODOs or the disorder sequence of TODO -> NEXT in the second one.

* Projects
:PROPERTIES:
:TRIGGER:  org-gtd-next-project-action org-gtd-update-project-task!
:ORG_GTD:  Projects
:END:

** Project 1 
*** TODO Task 1.1 
*** TODO Task 1.2

** Project 2
*** TODO Task 2.1 
*** NEXT Task 2.2

The idea is that the function could fix all the next todos at once instead of jumping to Project 1 first and then jumping to Project 2 to do the same.

Ideally, calling something like org-gtd-fix-todos-globally, the user could end with something like

* Projects
:PROPERTIES:
:TRIGGER:  org-gtd-next-project-action org-gtd-update-project-task!
:ORG_GTD:  Projects
:END:

** Project 1 
*** NEXT Task 1.1 
*** TODO Task 1.2

** Project 2
*** NEXT Task 2.1 
*** TODO Task 2.2

WDYT?

Best.