Log Message:
tex-l3kernel{,-doc}: update to 2023

- `\pdf_pagesize_gset:nn`
- Enable `\char_generate:nn` to create active tokens which are `\outer`
  or equal to `\fi`
- Added Complete list of pdfTeX primitives
- Allow for multi-part BCP47 strings in case changing
- Loading with plain TeX due to `\outer` status of `^^L`
  issue
- Leave catcode of `&` unchanged in code environment
- Allow for expressions within color `RGB`/`HSB` input
- Handling of multiple accents when uppercasing Greek
- Swap meaning of `el` and `el-x-iota` when case changing
  Greek: match traditional LaTeX approach
- Deprecated `\l_text_accents_tl` and `\l_text_letterlike_tl`
- More defensive approach in `\codepoint_to_nfd:n`
- CJK character handling for (u)pTeX
- `\tex_endlocalcontrol:D` as expl3 name for the LuaTeX primitive
- Allow non-integer values in color expressions
- Restrict color expressions values to the range [0, 100]
- Leave Greek spacing diacritics unchanged in uppercasing
- Fix minor version in `\c_sys_engine_version_str` for pdfTeX and LuaTeX