file input plugin: define watching_dir from include patterns

[DmitryRomanov]

try to define watching_dir from paths.include

see also #566

pipelines:
  welcome:
    input:
      type: file
      persistence_mode: async
      # watching_dir: /var/lib/docker/containers 
      # filename_pattern: "*-json.log"
      paths:
        include:
          - '/var/lib/docker/containers/30b28763e40a7649ef73c8afce0b0f4e62546f2a07a174d97e56bd02854facbd/*-json.log'
          - '/var/lib/docker/containers/65d343a9cc0a9fe6e466a370fcaf8ad6458eb912d19f8e8832e941e2ab7cafa0/*-json.log'
          - '/var/lib/docker/containers/**/*-json.log'
          - '/var/log/clickhouse-server/*.log'
        exclude:
          - '/var/lib/docker/overlay2/**'
          - '/var/lib/docker/volumes/**'
      offsets_file: ./offsets.yaml
      offsets_op: reset
    output:
      type: stdout

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 71.96262% with 30 lines in your changes missing coverage. Please review.

Project coverage is 71.02%. Comparing base (67ecc39) to head (d01873c). Report is 17 commits behind head on master.

:exclamation: Current head d01873c differs from pull request most recent head 9675047

Please upload reports for the commit 9675047 to get more accurate results.

Files	Patch %	Lines
plugin/input/file/watcher.go	75.29%	14 Missing and 7 partials :warning:
plugin/input/file/info.go	0.00%	9 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #567      +/-   ##
==========================================
+ Coverage   70.83%   71.02%   +0.18%     
==========================================
  Files         124      124              
  Lines       12572    12644      +72     
==========================================
+ Hits         8906     8981      +75     
+ Misses       3150     3141       -9     
- Partials      516      522       +6     

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