Add structured version info for modules wrapping external libraries

Feature or enhancement

Several modules wrap an external library, but expose its version inconsistently: only a string, only a plain tuple, only the runtime or only the build-time version, or under a private name. gh-117404 established a pattern for zlib, bz2, lzma and compression.zstd: a string and a named tuple for the version the module was built against (XXX_VERSION, XXX_VERSION_INFO), and the same pair for the library actually loaded (xxx_version, xxx_version_info).

Other modules (existing names, with their types):

• sqlite3 — runtime: sqlite_version (str), sqlite_version_info (plain tuple, computed in Python from the string). No build-time version.
• pyexpat — runtime: EXPAT_VERSION (str, e.g. 'expat_2.8.4'), version_info (plain tuple). No build-time version.
• decimal — runtime: __libmpdec_version__ (str). No tuple, no build-time version. Matters more now that only the system libmpdec is used.
• readline — build-time: _READLINE_VERSION (int, 0x0803). Runtime: _READLINE_RUNTIME_VERSION (int), _READLINE_LIBRARY_VERSION (str). All private; backend (str) tells readline from libedit.
• dbm.gnu — build-time: private _GDBM_VERSION (plain tuple). No runtime version (gdbm_version is not exposed).
• dbm.ndbm — only library (str, the implementation name). No version.
• ctypes — nothing about libffi.
• uuid — nothing about libuuid.
• ssl — runtime: OPENSSL_VERSION (str), OPENSSL_VERSION_INFO (plain 5-tuple), OPENSSL_VERSION_NUMBER (int). Build-time: only private _OPENSSL_API_VERSION (plain 5-tuple). The existing names conflict with the scheme above (uppercase names for the runtime version).
• curses — runtime: ncurses_version (named tuple). No string, no build-time version. It is fine to keep only the named tuple.
• tkinter — build-time: _tkinter.TCL_VERSION, TK_VERSION (str, only major.minor, e.g. '8.6'), and tkinter.TclVersion, TkVersion (float, 8.6, derived from them). The runtime version cannot be obtained at import time without creating a Tcl interpreter; it is available as Tcl().eval('info patchlevel').

Not all items need to be changed, and not all libraries provide both the compile-time and the runtime version. Sub-issues are opened for those that do.

Start by reading gh-117404 and comparing its zlib, bz2, lzma, and compression.zstd version API pattern with the module inventory in this issue. Review the relevant sub-issues and determine which modules can expose consistent build-time and runtime version information; done means each selected module has an agreed public interface without breaking existing names.