Make the plist parser slightly more tolerant (#47371)

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**Related issue:** Resolves #

# Checklist for submitter

If some of the following don't apply, delete the relevant line.

No changes file, already covered

- [x] Input data is properly validated, `SELECT *` is avoided, SQL
injection is prevented (using placeholders for values in statements), JS
inline code is prevented especially for url redirects, and untrusted
data interpolated into shell scripts/commands is validated against shell
metacharacters.
- [x] Timeouts are implemented and retries are limited to avoid infinite
loops
- [x] If paths of existing endpoints are modified without backwards
compatibility, checked the frontend/CLI for any necessary changes

## Testing

- [x] Added/updated automated tests
- [x] Where appropriate, [automated tests simulate multiple hosts and
test for host
isolation](https://github.com/fleetdm/fleet/blob/main/docs/Contributing/reference/patterns-backend.md#unit-testing)
(updates to one hosts's records do not affect another)

- [x] QA'd all new/changed functionality manually


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **Bug Fixes**
* Improved compatibility with multiple Apple plist format versions for
more reliable file handling.
* Strengthened validation of plist inputs to reduce false positives and
improve security.
* Adjusted early bounds checking so very short or malformed plist files
are handled more robustly.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

server/mdm/apple/plist_bounds.go

@@ -14,7 +14,9 @@ import (
 // dictionary of scalar values.
 const (
 	// binaryPlistMagic is the prefix that selects the binary plist decoder.
-	binaryPlistMagic = "bplist00"
+	// Apple doesn't fully document all versions, but "bplist00" and "bplist01" are known.
+	// Using "bplist0" lets us accept any "bplist0<digit>" version header.
+	binaryPlistMagic = "bplist0"
 	plistTrailerSize = 32
 
 	maxPlistObjects = 1 << 16 // distinct objects (offset-table size)
@@ -42,7 +44,8 @@ func BoundedPlistUnmarshal(data []byte, v any) error {
 // checkBinaryPlistBounds walks a binary plist's object references, rejecting
 // input that exceeds the limits or points outside the data region.
 func checkBinaryPlistBounds(data []byte) error {
-	if len(data) < len(binaryPlistMagic)+plistTrailerSize {
+	// See comment on binaryPlistMagic above for why the +1 is needed
+	if len(data) < len(binaryPlistMagic)+1+plistTrailerSize {
 		return fmt.Errorf("%w: shorter than minimum size", errMalformedPlist)
 	}