Fix host validation to support domain name

[wey-gu]

close: vesoft-inc/nebula-algorithm#42

This validation check only allowed IP format hosts, the domain name
should be supported on both thrift and HostAndPort.

This is blocking the nebula graph in K8s from using spark/java clients.

ref:

• https://github.com/google/guava/blob/master/guava/src/com/google/common/net/HostAndPort.java

[wey-gu]

This is a ref for hostname/IP addresses validation: https://gist.github.com/jyeary/d06f9980eb620216ff3a

[codecov-commenter]

Codecov Report

Merging #436 (df82ebf) into master (176a8f2) will decrease coverage by 0.32%.
The diff coverage is 0.00%.

@@             Coverage Diff              @@
##             master     #436      +/-   ##
============================================
- Coverage     63.58%   63.25%   -0.33%     
+ Complexity      730      726       -4     
============================================
  Files            66       66              
  Lines          3460     3462       +2     
  Branches        502      504       +2     
============================================
- Hits           2200     2190      -10     
- Misses          919      927       +8     
- Partials        341      345       +4     

Impacted Files	Coverage Δ
.../vesoft/nebula/client/meta/AbstractMetaClient.java	47.61% <0.00%> (-5.02%)	⬇️
...java/com/vesoft/nebula/client/meta/MetaClient.java	54.18% <0.00%> (-4.93%)	⬇️

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