refactor(auth): require valid token by default

[yggg]

Please read and mark the following check list before creating a pull request:

• I read and followed the CONTRIBUTING.md guide.
• I read and followed the New Feature Checklist guide.

Short description of what this resolves:

Closes #1246.

BREAKING CHANGE:
requireValidToken set to true by default.
Now if response contains invalid token NbAuthIllegalTokenError is thrown.
To enable old behavior, set requireValidToken: false in the auth strategy method config, e.g.:

NbPasswordAuthStrategy.setup({
  // ...
  login: {
    // ...
    requireValidToken: false,
  },
});

or

NbOAuth2AuthStrategy.setup({
  // ...
  authorize: {
    // ...
    requireValidToken: false,
  },
});

[nnixaa]

lgtm

[codecov]

Codecov Report

Merging #2259 into master will decrease coverage by 0.04%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2259      +/-   ##
==========================================
- Coverage   81.65%   81.61%   -0.05%     
==========================================
  Files         244      244              
  Lines        7359     7359              
  Branches      771      771              
==========================================
- Hits         6009     6006       -3     
- Misses       1122     1126       +4     
+ Partials      228      227       -1

Impacted Files	Coverage Δ
...ramework/auth/strategies/oauth2/oauth2-strategy.ts	83.57% <ø> (ø)	⬆️
...h/strategies/password/password-strategy-options.ts	100% <ø> (ø)	⬆️
.../auth/strategies/oauth2/oauth2-strategy.options.ts	100% <ø> (ø)	⬆️
...work/auth/strategies/password/password-strategy.ts	97.59% <ø> (ø)	⬆️
...ramework/theme/components/toastr/toastr.service.ts	94.78% <0%> (-2.61%)	⬇️