luci-proto-modemmanager: fix ACL command injection

luci-proto-modemmanager: fix ACL command injection

The ACL permissions were originally authored to support just a single
set of modem interfaces, at the numbers 0-9.  Eventually this was
adjusted to support from 0 to 999 avoiding command injection.

However, as new commands were added, this was reverted again
unfortunately. Language like "regex" has been used in the commit history
for this ACL, and likely the core of the issue is confusion on how these
are parsed.  These are all parsed [1] with fnmatch(...), and not regex(..).

A future useful change could be for rpcd to set the FNM_EXTMATCH option
for fnmatch(...) to simplify this particular match statement, but that's
not considered here since that's a much broader change that needs a
longer discussion.

[1] https://github.com/openwrt/rpcd/blob/a4a5a298588960638a2e1713eb8fb858e1dbedeb/session.c#L143-L147

Fixes: 54aa70112c ("luci-proto-modemmanager: add status page")
Signed-off-by: Tim Nordell <redacted>