build: execute CI workflows based on which files are modified

[morrisonlevi]

Description

This uses CircleCI's dynamic configuration to execute specific workflows based on which files are modified. It does this by comparing the changed files to the master branch, so in a stacked PR scenario, you may run more tests than you expect.

The build and build_packages workflows are on by default, and currently no rules disable them. The workflows which are enabled this way are:

• components
• zend_abstract_interface
• profiling (new, this is just the profiling tests extracted to a workflow so they can be conditionally run and tracked individually)

Note that the eclint job is broken when ran from a CircleCI continuation because of the gulp-reporter, which hard-codes the configuration as .circleci/config.yml, which is broken by using .circleci/continue_config.yml. It seems eclint is unmaintained, and has been for around 5 years now. We could copy the lint job to the main workflow if we want, or we could drop the eclint check instead. For now I have removed it.

These PRs demonstrate the filters work correctly for the relevant workflows (but disabled the build workflows to save credits, as they aren't needed).

• build: components run if components/ dir changes #2066
• build: profiling workflow runs if ext/handlers_api.h changes #2067
• build: zai workflow runs if something in zend_abstract_interface changes #2068

Readiness checklist

• Changelog has been added to the release document.
• Tests added for this feature/bug. Draft PRs test the job continuations, but this just a one time test.

Reviewer checklist

• Appropriate labels assigned.
• Milestone is set.

[bwoebi]

Trusting that it's working, and the pipeline conditions seem sensible.