Support hdfs path as 'hdfs://nameservice'

[kyungwan-nam]

#3576

It works well as below.

juicefs format \
     --storage hdfs \
     --bucket hdfs://example/user/kyungwan-nam \
     --access-key kyungwan-nam \
     sqlite3://myjfs.db \
     myjfs

2023/05/10 11:59:03.763603 juicefs[48742] <INFO>: Meta address: sqlite3://myjfs.db [interface.go:492]
2023/05/10 11:59:03.767982 juicefs[48742] <INFO>: HDFS Addresses: nn1.example.com:8020,nn2.example.com:8020, basePath: /user/kyungwan-nam/ [hdfs.go:351]
2023/05/10 11:59:03.768783 juicefs[48742] <INFO>: username: kyungwan-nam, realm: EXAMPLE.COM [hdfs_kerberos.go:46]
2023/05/10 11:59:03.793293 juicefs[48742] <INFO>: Data use hdfs://nn1.example.com:8020,nn2.example.com:8020/user/kyungwan-nam/myjfs/ [format.go:450]
2023/05/10 11:59:04.190378 juicefs[48742] <INFO>: Volume is formatted as {
  "Name": "myjfs",
  "UUID": "xxxx",
  "Storage": "hdfs",
  "Bucket": "hdfs://example/user/kyungwan-nam",
  "AccessKey": "kwnam",
  "BlockSize": 4096,
  "Compression": "none",
  "EncryptAlgo": "aes256gcm-rsa",
  "TrashDays": 1,
  "MetaVersion": 1
} [format.go:487]

[codecov-commenter]

Codecov Report

Patch coverage: 24.00% and project coverage change: -0.15 ⚠️

Comparison is base (83258be) 56.11% compared to head (a568453) 55.97%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3577      +/-   ##
==========================================
- Coverage   56.11%   55.97%   -0.15%     
==========================================
  Files         149      149              
  Lines       36994    37015      +21     
==========================================
- Hits        20760    20719      -41     
- Misses      13955    14009      +54     
- Partials     2279     2287       +8     

Impacted Files	Coverage Δ
pkg/object/hdfs.go	62.14% <24.00%> (-3.89%)	⬇️

... and 9 files with indirect coverage changes

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