vmware: derive the NetBox VM name and description with vm_name_regex

[semx]

vm_name_regex for #465: a regex applied to the vCenter VM name before any other name handling. Its named group name becomes the NetBox VM name; an optional named group description fills the VM's description. A name the regex does not match is used unchanged (one debug2 line says so), and strip_vm_domain_name still runs afterwards. The option is unset by default, so nothing changes without it.

The example from the issue, ^(?P<name>[^ (]+)(?: \((?P<description>.*)\))?$, turns web01 (production) into the VM web01 with description production. A regex without a name group, or one that does not compile, is rejected when the config is loaded. A name group that takes no part in the match (an optional group) or matches only whitespace leaves the name unchanged with a warning, so a permissive pattern cannot produce a VM without a name. An empty description group sets nothing; a description already in NetBox is kept in that case, the way comments are. A result longer than the NetBox field (64 for the name, 200 for the description) is reported before NetBox cuts it. The description is only sent to NetBox 3.4 and later, where the field exists.

Renaming matters for matching: a VM whose NetBox name changes is no longer found by name + cluster and falls back to the MAC, IP and serial matching that already exists. The resulting name is also what vm_include_filter, vm_exclude_filter and the vm_*_relation options see, and it has to stay unique per cluster: two VMs that rewrite to the same name are reported as duplicates (the warning names the option) and the second is skipped, as before. On a live NetBox 4.7.2 with the vc001 inventory and ^(?P<name>vm\d+)_(?P<description>.*)$, the 18 VMs the regex matched were renamed in place (18 PATCH, no POST, 34 VMs before and after) and got their description; the second run wrote nothing. Users who enable this on an existing NetBox should expect that one-off rename.

Tests: tests/test_vmware_vm_name_regex.py (16): match with and without the description group, a non-matching name, the optional and the blank name group, the empty description group, anchoring at the start of the name, the length warnings, the strip_vm_domain_name order, the unset default, load-time rejection of a regex without the name group and of one that does not compile, and one vcsim run asserting the description lands on the VM object. All 15 test runs fail on development without this change (the vcsim one is skipped on the second capture). Full suite: 295 passed, 1 skipped (development: 280). With the option unset the handler produces the same inventory as development on vc001: 324 objects, byte-identical canonical dump.