[lldb] Reland: Store SupportFile in FileEntry (NFC) (#85892)

This is another step towards supporting DWARF5 checksums and inline
source code in LLDB. This is a reland of #85468 but without the
functional change of storing the support file from the line table (yet).

GitOrigin-RevId: 556fe5f290ea88dcbb7ced16b0f057dcebce1fd0
27 files changed