Rename the ext/misc/analyze.c extension to ext/misc/diskused.c, to avoid

confusion with the src/analyze.c file.  The function is now called
"diskused(X)" instead of "analyze(X)".  The CLI command is renamed
from ".dbstat" to ".diskused".

FossilOrigin-Name: c7839f7a1749b38f8a36c06d93a7b59095e91ce753e8dd020de273ca8f73a239