mirror command ignores netclass labels
# Description
The mirror-command in eeschema ignores:
- netclass directive labels
- optionally added netclass-fields in other labels
- optionally added custom user fields in all labels
This happens if the mirror-command is executed on a selection (containg multiple items). It does not happen if a netclass label is individually mirrored.
# Steps to reproduce
1. open attached project, open schematic: [mirror_labels.zip](/uploads/d6857e48c7edffee18082d9b31c6a092/mirror_labels.zip)
2. block-select the schematic portion around J7 (top left), see picture 1
3. "X" to mirror , also try "Y"
4. look and judge the result - the netclass-strings and the optional user-field-strings are not mirrored (see picture 2)

# KiCad Version
```
Application: KiCad Schematic Editor x64 on x64
Version: 7.0.3-7-gdf698b9433, release build
Libraries:
wxWidgets 3.2.2
FreeType 2.12.1
HarfBuzz 6.0.0
FontConfig 2.14.1
libcurl/7.88.1-DEV Schannel zlib/1.2.13
Platform: Windows 10 (build 19045), 64-bit edition, 64 bit, Little endian, wxMSW
Build Info:
Date: May 17 2023 05:13:21
wxWidgets: 3.2.2 (wchar_t,wx containers)
Boost: 1.81.0
OCC: 7.6.3
Curl: 7.88.1-DEV
ngspice: 40
Compiler: Visual C++ 1934 without C++ ABI
Build settings:
KICAD_SPICE=ON
```
issue