[Proposal] Add regex matcher

[tmshn]

What I did

Yet jmespath is powerful, there's still room for a improvement on string-based query.
In this PR, I added regex matcher, like Jayway's jsonpath do.
I believe this will bring greater power to query on complex data.

All I did is implementation, and is nothing to do with specs or docs.

c.f.: jmespath/jmespath.site#29

Example

Given:

{
  "sshd_configs": [
    {"hostname": "bastion", "body": "Port 22\nPort 443\n#ListenAddress ::\n#ListenAddress 0.0.0.0\n"},
    {"hostname": "web1", "body": "Port 22\nListenAddress 192.168.1.10\n"},
    {"hostname": "web2", "body": "Port 22\n#ListenAddress 192.168.1.10\n"}
  ]
}

Then,

sshd_configs[? body =~ /^Port 443/m].hostname

👉 ["bastion"]

or,

sshd_configs[? body =~ /^#?ListenAddress\s+192\.168\.\d+\.\d+/m].hostname

👉 ["web1", "web2"]

[codecov-io]

Codecov Report

Merging #148 into develop will decrease coverage by 0.18%.
The diff coverage is 91.48%.

@@             Coverage Diff             @@
##           develop     #148      +/-   ##
===========================================
- Coverage    97.25%   97.06%   -0.19%     
===========================================
  Files           14       14              
  Lines         1455     1500      +45     
===========================================
+ Hits          1415     1456      +41     
- Misses          40       44       +4

Impacted Files	Coverage Δ
tests/test_lexer.py	98.78% <100%> (+0.16%)	⬆️
jmespath/parser.py	99.68% <100%> (ø)	⬆️
jmespath/visitor.py	98.19% <81.81%> (-0.86%)	⬇️
jmespath/lexer.py	98.14% <91.66%> (-1.14%)	⬇️

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[danihodovic]

This is great! A jmespath matcher in Ansible is exactly what I need.

Are there any plans on merging this soon?