fix: support nullable bool value set in config

[Ace-Tang]

make nullable value like false and 0 not be recognized as
empry value, in config set, they should be valid value.

Signed-off-by: Ace-Tang [email protected]

Ⅰ. Describe what this PR did

Ⅱ. Does this pull request fix one issue?

Ⅲ. Describe how you did it

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews

[codecov-io]

Codecov Report

Merging #1502 into master will decrease coverage by 0.91%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master    #1502      +/-   ##
==========================================
- Coverage   40.56%   39.64%   -0.92%     
==========================================
  Files         254      254              
  Lines       16537    16891     +354     
==========================================
- Hits         6708     6697      -11     
- Misses       8966     9329     +363     
- Partials      863      865       +2

Impacted Files	Coverage Δ
pkg/utils/utils.go	85.27% <0%> (-0.36%)	⬇️
daemon/mgr/spec_mount.go	54.54% <0%> (-15.67%)	⬇️
apis/server/utils.go	59.52% <0%> (-4.77%)	⬇️
ctrd/watch.go	75% <0%> (-3.13%)	⬇️
daemon/mgr/network.go	68.94% <0%> (-0.49%)	⬇️
daemon/mgr/container.go	49.2% <0%> (-0.09%)	⬇️
cri/v1alpha2/cri.go	0% <0%> (ø)	⬆️
cri/v1alpha1/cri.go	0% <0%> (ø)	⬆️

[rudyfly]

LGTM