feat(typescript-estree): correct logic used to escape string literals

[armano2]

This PR add correct unescaping of xhml string literals and jsxText that is now applied only in jsx context.

logic for this PR has been crafted base on current implementaion of acorn-jsx and babel

https://github.com/acornjs/acorn-jsx/blob/master/index.js
https://github.com/babel/babel/blob/main/packages/babel-parser/src/plugins/jsx/index.js

notable changes:

• instead of using lodash unescape funtion that offers limited number of escape characters &, <, >, ", ' we will now handle all valid values, additionally support for unescaping hex and decimal codepoints has been added.

see: https://github.com/lodash/lodash/blob/2f79053d7bc7c9c9561a30dda202b3dcd2b72b90/unescape.js#L2

#2279

[codecov]

Codecov Report

Merging #2995 (9bd550f) into master (ee927ee) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #2995   +/-   ##
=======================================
  Coverage   92.71%   92.72%           
=======================================
  Files         313      314    +1     
  Lines       10658    10663    +5     
  Branches     3019     3023    +4     
=======================================
+ Hits         9882     9887    +5     
  Misses        355      355           
  Partials      421      421           

Flag	Coverage Δ
unittest	92.72% <100.00%> (+<0.01%)	⬆️

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Impacted Files	Coverage Δ
packages/typescript-estree/src/convert.ts	98.37% <100.00%> (-0.01%)	⬇️
...ckages/typescript-estree/src/jsx/xhtml-entities.ts	100.00% <100.00%> (ø)
packages/typescript-estree/src/node-utils.ts	97.77% <100.00%> (+0.08%)	⬆️