fix: percent-encode vCenter datacenter/cluster/host names in virt-v2v URIs

[waterWang]

Fixes #13920

Summary

LibvirtConvertInstanceCommandWrapper builds vpx:// and vi:// connection URIs for virt-v2v by concatenating vCenter datacenter/cluster/host names without percent-encoding them. A datacenter (or cluster/host) name containing a space — valid in vSphere — produces an invalid URI, and VM import from VMware fails.

Changes

• encodePathSegment — percent-encodes a single URI path segment using %20 for spaces (not +)
• encodePathSegments — splits on / and encodes each sub-segment individually, preserving literal / separators for folder-nested names (e.g. MyFolder/MyDC)
• buildVpxUrl — now calls encodePathSegments on datacenter and cluster, encodePathSegment on host
• getExportOVAUrlFromRemoteInstance — now calls encodePathSegments on datacenter and path, encodePathSegment on vm
• encodeUsername — fixed to use explicit UTF-8 charset and %20 instead of + for spaces (libvirt only decodes %20 in URI authority segments)

Testing

Manual test: with a datacenter named QA Lab, the vpx:// URL now correctly becomes:

vpx://Administrator%40vsphere.local@203.0.113.10/QA%20Lab/cluster-a/203.0.113.20?no_verify=1

[DaanHoogland]

@waterWang you are adding a lot of PRs, thanks. Very welcome. You are basing all your PRs of main, though the reports/issues are on 4.22 for the most time. Do you think you can rebase them?