Make GraphQL packages peer dependencies

[MichalLytek]

This PR makes graphql and @types/graphql a peer dependencies. This will allow for better interop with other GraphQL ecosystem libraries without version conflict issues.

It also introduces the strict version check in runtime using node-semver to ensure that users update the peer dependencies on TypeGraphQL update - this trick will limit all weird runtime errors that might occur when TypeGraphQL uses some new graphql-js features.

[codecov]

Codecov Report

Merging #239 into master will increase coverage by 0.08%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #239      +/-   ##
==========================================
+ Coverage   95.49%   95.57%   +0.08%     
==========================================
  Files          65       67       +2     
  Lines        1043     1063      +20     
  Branches      186      187       +1     
==========================================
+ Hits          996     1016      +20     
  Misses         46       46              
  Partials        1        1

Impacted Files	Coverage Δ
src/utils/graphql-version.ts	100% <100%> (ø)
src/errors/index.ts	100% <100%> (ø)	⬆️
src/errors/UnmetGraphQLPeerDependencyError.ts	100% <100%> (ø)
src/schema/schema-generator.ts	97.12% <100%> (+0.02%)	⬆️

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