Allow build.commands without build.tools

[benjaoming]

• update tests
• update validate
• check everything else that depends on some assumption

Fixes #9280

[benjaoming]

Tested on https://github.com/readthedocs/test-builds/tree/bare-commands

[benjaoming]

It works! But maybe we should add more documentation about the fact that the directory needs to be created?

https://docs.readthedocs.io/en/stable/build-customization.html#where-to-put-files

[benjaoming]

@humitos I made a "positive" test (manually) to see that a build like this works. But is there something else to be aware of?

[humitos]

It works! But maybe we should add more documentation about the fact that the directory needs to be created?

I think adding just one sentence in the link you pasted mentioning this in the documentation is enough.

[humitos]

But is there something else to be aware of?

When working with the build process, I recommend you to always test locally a bunch of use-cases/branches from the test-builds repository -- not only the exact case you want to make it work. It can be tricky multiple times 😄

[humitos]

Looks good, I think we are close to be able to merge it.

[benjaoming]

I think adding just one sentence in the link you pasted mentioning this in the documentation is enough.

Added as a note box. I think it's great to add it in this PR :)

[benjaoming]

But is there something else to be aware of?

When working with the build process, I recommend you to always test locally a bunch of use-cases/branches from the test-builds repository -- not only the exact case you want to make it work. It can be tricky multiple times 😄

I'll be trying out different branches that look relevant and get back 👍

[benjaoming]

I did a bunch of builds searching for branch names containing "jobs" and "tools" and "commands" in test-builds and didn't find any positive negatives. The failing branches are failing later in the build.