dev: use bool pointer on deprecated bool options

[ldez]

Replaces bool by bool pointer to detect explicit false or true inside the configuration.

linters-settings:
  copyloopvar:
    ignore-alias: false
  govet:
    check-shadowing: false
  usestdlibvars:
    os-dev-null: false
    syslog-priority: false
  unused:
    exported-is-used: false

issues:
  exclude-generated-strict: false

output:
  uniq-by-line: false

run:
  show-stats: false
  skip-dirs-use-default: false

$ golangci-lint run
WARN [config_reader] The configuration option `run.skip-dirs-use-default` is deprecated, please use `issues.exclude-dirs-use-default`. 
WARN [config_reader] The configuration option `run.show-stats` is deprecated, please use `output.show-stats` 
WARN [config_reader] The configuration option `output.uniq-by-line` is deprecated, please use `issues.uniq-by-line` 
WARN [config_reader] The configuration option `issues.exclude-generated-strict` is deprecated, please use `issues.exclude-generated` 
WARN [config_reader] The configuration option `linters.govet.check-shadowing` is deprecated. Please enable `shadow` instead, if you are not using `enable-all`. 
WARN [config_reader] The configuration option `linters.copyloopvar.ignore-alias` is deprecated and ignored,please use `linters.copyloopvar.check-alias`. 
WARN [config_reader] The configuration option `linters.unused.exported-is-used` is deprecated. 
WARN [config_reader] The configuration option `linters.usestdlibvars.os-dev-null` is deprecated. 
WARN [config_reader] The configuration option `linters.usestdlibvars.syslog-priority` is deprecated.