fix(ts-estree): make sure that every node can be converted to tsNode

[armano2]

This PR makes sure that all nodes can be converted into ts.Node and fixes crash in promise-function-async rule

fixes: #227

[codecov]

Codecov Report

Merging #287 into master will decrease coverage by 0.07%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #287      +/-   ##
==========================================
- Coverage   95.03%   94.96%   -0.08%     
==========================================
  Files          67       67              
  Lines        2801     2801              
  Branches      724      724              
==========================================
- Hits         2662     2660       -2     
  Misses         53       53              
- Partials       86       88       +2

Impacted Files	Coverage Δ
packages/typescript-estree/src/node-utils.ts	96.62% <ø> (-0.23%)	⬇️
packages/typescript-estree/src/convert.ts	98.23% <100%> (+0.02%)	⬆️
.../eslint-plugin/src/rules/promise-function-async.ts	100% <100%> (ø)	⬆️
...slint-plugin/src/rules/no-unnecessary-qualifier.ts	90.9% <0%> (-3.64%)	⬇️

[armano2]

no-unnecessary-qualifier can be now simplified

      'ExportNamedDeclaration[declaration.type="TSModuleDeclaration"]': enterDeclaration,
      'ExportNamedDeclaration[declaration.type="TSEnumDeclaration"]': enterDeclaration,
      'ExportNamedDeclaration[declaration.type="TSModuleDeclaration"]:exit': exitDeclaration,
      'ExportNamedDeclaration[declaration.type="TSEnumDeclaration"]:exit': exitDeclaration,

is no longer needed

and ifs

if (esTreeNodeToTSNodeMap.has(node)) {

if (tsDeclaration) {

can be removed