fix(reflect): handle deep get of map with dot(s) in key name

[buchdag]

This PR fixes #679

[buchdag]

compose.yaml

services:
  app:
    scale: 22
    image: nginx:1.27-alpine
    labels:
      com.example.haproxy.backend: "true"

test.tmpl

{{ $containers := sortObjectsByKeysAsc (whereLabelValueMatches . "com.example.haproxy.backend" "true") "Labels.com.docker.compose.container-number" }}
{{ range $index, $container := $containers }}
{{ $index }} - {{ $container.Name }}: {{ index $container.Labels "com.docker.compose.container-number" }}
{{ end }}

➜  docker-gen git:(fix/679) ✗ ./docker-gen wip/test.tmpl
0 - wip-app-1: 1
1 - wip-app-2: 2
2 - wip-app-3: 3
3 - wip-app-4: 4
4 - wip-app-5: 5
5 - wip-app-6: 6
6 - wip-app-7: 7
7 - wip-app-8: 8
8 - wip-app-9: 9
9 - wip-app-10: 10
10 - wip-app-11: 11
11 - wip-app-12: 12
12 - wip-app-13: 13
13 - wip-app-14: 14
14 - wip-app-15: 15
15 - wip-app-16: 16
16 - wip-app-17: 17
17 - wip-app-18: 18
18 - wip-app-19: 19
19 - wip-app-20: 20
20 - wip-app-21: 21
21 - wip-app-22: 22