Add nf_conntrack as module

I'm trying to run k0s inside of WSL2 instance, but I got this problem on kube-proxy:
```
I0725 04:49:28.961290 1 node.go:163] Successfully retrieved node IP: 172.30.14.123
I0725 04:49:28.961316 1 server_others.go:109] "Detected node IP" address="172.30.14.123"
E0725 04:49:28.967749 1 proxier.go:670] "Failed to read builtin modules file, you can ignore this message when kube-proxy is running inside container without mounting /lib/modules" err="open /lib/modules/5.15.90.1-microsoft-standard-WSL2/modules.builtin: no such file or directory" filePath="/lib/modules/5.15.90.1-microsoft-standard-WSL2/modules.builtin"
I0725 04:49:28.968848 1 proxier.go:680] "Failed to load kernel module with modprobe, you can ignore this message when kube-proxy is running inside container without mounting /lib/modules" moduleName="ip_vs"
I0725 04:49:28.969416 1 proxier.go:680] "Failed to load kernel module with modprobe, you can ignore this message when kube-proxy is running inside container without mounting /lib/modules" moduleName="ip_vs_rr"
I0725 04:49:28.970035 1 proxier.go:680] "Failed to load kernel module with modprobe, you can ignore this message when kube-proxy is running inside container without mounting /lib/modules" moduleName="ip_vs_wrr"
I0725 04:49:28.970623 1 proxier.go:680] "Failed to load kernel module with modprobe, you can ignore this message when kube-proxy is running inside container without mounting /lib/modules" moduleName="ip_vs_sh"
I0725 04:49:28.971291 1 proxier.go:680] "Failed to load kernel module with modprobe, you can ignore this message when kube-proxy is running inside container without mounting /lib/modules" moduleName="nf_conntrack"
E0725 04:49:28.971347 1 server.go:492] "Error running ProxyServer" err="can't use the IPVS proxier: IPVS proxier will not be used because the following required kernel modules are not loaded: [ip_vs_wrr ip_vs_sh ip_vs ip_vs_rr]"
E0725 04:49:28.971364 1 run.go:74] "command failed" err="can't use the IPVS proxier: IPVS proxier will not be used because the following required kernel modules are not loaded: [ip_vs_wrr ip_vs_sh ip_vs ip_vs_rr]"
I0725 04:52:17.678267 1 server.go:432] "Using lenient decoding as strict decoding failed" err="strict decoding error: unknown field \"udpIdleTimeout\""
W0725 04:52:17.678330 1 feature_gate.go:241] Setting GA feature gate ServiceInternalTrafficPolicy=true. It will be removed in a future release.
W0725 04:52:17.678372 1 feature_gate.go:241] Setting GA feature gate ServiceInternalTrafficPolicy=true. It will be removed in a future release.
I0725 04:52:17.690601 1 node.go:163] Successfully retrieved node IP: 172.30.14.123
I0725 04:52:17.690627 1 server_others.go:109] "Detected node IP" address="172.30.14.123"
E0725 04:52:17.696504 1 proxier.go:670] "Failed to read builtin modules file, you can ignore this message when kube-proxy is running inside container without mounting /lib/modules" err="open /lib/modules/5.15.90.1-microsoft-standard-WSL2/modules.builtin: no such file or directory" filePath="/lib/modules/5.15.90.1-microsoft-standard-WSL2/modules.builtin"
I0725 04:52:17.697137 1 proxier.go:680] "Failed to load kernel module with modprobe, you can ignore this message when kube-proxy is running inside container without mounting /lib/modules" moduleName="ip_vs"
I0725 04:52:17.697737 1 proxier.go:680] "Failed to load kernel module with modprobe, you can ignore this message when kube-proxy is running inside container without mounting /lib/modules" moduleName="ip_vs_rr"
I0725 04:52:17.698300 1 proxier.go:680] "Failed to load kernel module with modprobe, you can ignore this message when kube-proxy is running inside container without mounting /lib/modules" moduleName="ip_vs_wrr"
I0725 04:52:17.698847 1 proxier.go:680] "Failed to load kernel module with modprobe, you can ignore this message when kube-proxy is running inside container without mounting /lib/modules" moduleName="ip_vs_sh"
I0725 04:52:17.699387 1 proxier.go:680] "Failed to load kernel module with modprobe, you can ignore this message when kube-proxy is running inside container without mounting /lib/modules" moduleName="nf_conntrack"
E0725 04:52:17.699426 1 server.go:492] "Error running ProxyServer" err="can't use the IPVS proxier: IPVS proxier will not be used because the following required kernel modules are not loaded: [ip_vs_wrr ip_vs_sh ip_vs ip_vs_rr]"
E0725 04:52:17.699439 1 run.go:74] "command failed" err="can't use the IPVS proxier: IPVS proxier will not be used because the following required kernel modules are not loaded: [ip_vs_wrr ip_vs_sh ip_vs ip_vs_rr]"
```
We are using IPVS indeed and those modules are required.

Start by locating the WSL kernel module configuration and checking how nf_conntrack is enabled or packaged for WSL2. Verify the resulting kernel exposes nf_conntrack so kube-proxy can load it for IPVS; the issue does not name a source file or test.

Written by the indexing model from the issue text.