feat(eslint-plugin): [unbound-method] support constructor binding

[sergey-shulyak]

fix #636

[typescript-eslint]

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[codecov]

Codecov Report

Merging #1105 into master will decrease coverage by 0.02%.
The diff coverage is 90.9%.

@@            Coverage Diff             @@
##           master    #1105      +/-   ##
==========================================
- Coverage   94.09%   94.07%   -0.03%     
==========================================
  Files         120      120              
  Lines        5203     5216      +13     
  Branches     1443     1444       +1     
==========================================
+ Hits         4896     4907      +11     
- Misses        176      177       +1     
- Partials      131      132       +1

Impacted Files	Coverage Δ
packages/typescript-estree/src/parser.ts	95.61% <100%> (+0.03%)	⬆️
...pt-estree/src/create-program/createWatchProgram.ts	93.16% <100%> (+0.17%)	⬆️
...ges/typescript-estree/src/create-program/shared.ts	78.57% <72.72%> (-4.77%)	⬇️

[bradzacher]

only doing this on assignment expressions is too strict of a check.

I.e. these cases will be missed.

myFunc(this.clazz.bind(this));
true || this.clazz.bind(this);
return this.clazz.bind(this);

[bradzacher]

This is not a strong enough check.
I.e. it will false positive in these cases, which are clearly improperly bound:

this.handleSomething.bind();
this.handleSomething.bind(null);
this.handleSomething.bind(undefined);