feat(lib): 创建家目录时设置权限为740

[ZihanChen821]

改动：
insertKeyAsRoot时会创建家目录，之前的权限默认为755， 不希望其他用户可以读以及访问该家目录，故创建家目录时设定权限为740

结果：
新用户创建后家目录如下

[changeset-bot]

🦋 Changeset detected

Latest commit: aceba0d

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 8 packages

Name	Type
@scow/lib-ssh	Patch
@scow/auth	Patch
@scow/mis-server	Patch
@scow/portal-server	Patch
@scow/portal-web	Patch
@scow/gateway	Patch
@scow/mis-web	Patch
@scow/cli	Patch

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (e1e3230) 68.89% compared to head (aceba0d) 68.90%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #953   +/-   ##
=======================================
  Coverage   68.89%   68.90%           
=======================================
  Files         132      132           
  Lines        3926     3927    +1     
  Branches      523      523           
=======================================
+ Hits         2705     2706    +1     
  Misses       1123     1123           
  Partials       98       98           

Files	Coverage Δ
libs/ssh/src/key.ts	90.00% <100.00%> (+0.16%)	⬆️

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[ddadaal]

为什么要740？在PR里解释一下