Support .aemignore in addition to .hlxignore

[trieloff]

If both are present, .aemignore` should win

see https://main--helix-website--adobe.aem.page/developer/anatomy-of-a-franklin-project#dont-serve-hlxignore

[kptdobe]

I wanted to rename .hlxignore file to .aemignore in our boilerplate projects but I found out this issue, i.e. it is not supported. We need to get rid of the hlx prefix in projects.

To be a good citizen, I wanted to create a PR but I realized it is not so trivial, especially because we need to fetch one file then the other one if request fails (whichever has prio), this might some failing requests and slow down the process. See https://github.com/adobe/helix-shared/blob/main/packages/helix-shared-config/src/IgnoreConfig.js and https://github.com/adobe/helix-shared/blob/main/packages/helix-shared-config/src/BaseConfig.js#L170-L189.

Finally, I found https://github.com/adobe/helix-admin-support/blob/main/src/fetch-ignore.js#L61 which shows me this is much more subtile than expected.

Anyone wants to look at this one ? @maxakuru @dominique-pfister @tripodsan (found your names in the area).

[dominique-pfister]

There are other projects that would need to be enhanced as well:

• @adobe/helix-ctl: https://github.com/adobe/helix-ctl/blob/c32affef6b929e922318459c3c85250a44d27f8b/src/cmds/code_cmds/fix.js#L31
• @adobe/helix-admin: https://github.com/adobe/helix-admin/blob/99991051a245091ffe0ee09d90534f43ba5dd395/src/codebus/code-job.js#L223