feat(dev-infra): pullapprove verify should handle files in conditions (#36661)

Currently, when verifying our pullapprove configuration, we don't
respect modifications to the set of files in a condition.

e.g. It's not possible to do the following:

```
contains_any_globs(files.exclude(...), [
```

This prevents us from having codeowner groups which match a directory,
but want to filter out specific sub directories. For example, `fw-core`
matches all files in the core package. We want to exclude the schematics
from that glob. Usually we do this by another exclude condition.

This has a *significant* downside though. It means that fw-core will not
be requested if a PR changes schematic code, _and_ actual fw-core code.

To support these conditions, the pullapprove verification tool is
refactored, so that it no longer uses Regular expressions for parsing,
but rather evaluates the code through a dynamic function. This is
possible since the conditions are written in simple Python that can
be run in NodeJS too (with small modifications/transformations).

PR Close #36661

dev-infra/pullapprove/parse-yaml.ts

@@ -8,7 +8,7 @@
 import {parse as parseYaml} from 'yaml';
 
 export interface PullApproveGroupConfig {
-  conditions?: string;
+  conditions?: string[];
   reviewers: {
     users: string[],
     teams?: string[],