dirstatemap: add a common `_insert_entry` method for dirstatemap
This method is called to add a new DirstateItem to the map.
Each variant have a different implementation (which is … the point).
Differential Revision: https://phab.mercurial-scm.org/D11573
# See http://EditorConfig.org for the specification
root = true
[*.py]
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indent_style = space
trim_trailing_whitespace = true
end_of_line = lf
[*.{c,h}]
indent_size = 8
indent_style = tab
trim_trailing_whitespace = true
end_of_line = lf
[*.t]
indent_size = 2
indent_style = space
trim_trailing_whitespace = false
end_of_line = lf