Do not use "simplify history" features for "File History"
Do not use "simplify history" features for "File History"

Fixes #1301

As explained in https://git-scm.com/docs/git-log#_history_simplification
`<file_paths>`, `--simplify-by-decoration`, and `--sparse` interact.

For the common "Repo History" "sparse" is easy to follow and to
understand, but when showing a "File History" it is not a good default
mode anymore. The settings "--sparse", "--dense" etc. become rather fine
grained research methods. Git's "Default mode" (again see their docs)
becomes the only understandable mode.

So we just follow here and use history simplification only when showing
the "Repo History".

divmain/GitSavvy,divmain/GitSavvy,divmain/GitSavvy