Config to exclude commits from git blame

[salcode]

If a repo has a .git-blame-ignore-revs file, any commits in that file will be excluded from the results of "git blame".

Additionally, this configuration modifies the git blame output so that:

• A "?" is added to the line if the output was modified by this ignoring
• A "*" is added if no commit can be associated with the line (because the commit that added the line is ignored)

See https://michaelheap.com/git-ignore-rev/

[salcode]

If a repo does not have a .git-blame-ignore-revs file, we get the error

fatal: could not open object name list: .git-blame-ignore-revs

There is discussion around this topic but no solution as of yet

• Issues with git config blame. ignorerevsfile when file not found
• git blame with optional ignorerevsfile

As such it seems like adding a .git-blame-ignore-revs file to a repo is a good idea however there is no global Git configuration to read this file ☹️

[salcode]

Closing this PR since it doesn't seem this is going to work. ☹️