infra(typescript-eslint): prefer-regexp-exec

[ST-DDT]

Companion PR for #2435. This applies the changes from #2108 to newer code and ensures future code abides to the same rules.

• infra: enable strictNullChecks in tsconfig #2435
• chore: improve regex usage #2108

---

Enables the @typescript-eslint/prefer-regexp-exec lint rule.

---

Reasoning: Regexp.exec behaves the same as string.match(RegExp) without /g flag, with the main difference being that exec gurantees the index to be present:

interface RegExpMatchArray extends Array<string> {
    /**
     * The index of the search at which the result was found.
     */
    index?: number;
    [...]
}

interface RegExpExecArray extends Array<string> {
    /**
     * The index of the search at which the result was found.
     */
    index: number;
    [...]
}

string.match(RegExp) without /g flag, also returns the index, but requires the not null assertion qualifier!.

[codecov]

Codecov Report

Merging #2466 (a29d2aa) into next (c033044) will increase coverage by 0.00%.
The diff coverage is 100.00%.

Additional details and impacted files

@@           Coverage Diff           @@
##             next    #2466   +/-   ##
=======================================
  Coverage   99.58%   99.59%           
=======================================
  Files        2823     2823           
  Lines      255517   255517           
  Branches     1103     1105    +2     
=======================================
+ Hits       254466   254474    +8     
+ Misses       1023     1015    -8     
  Partials       28       28           

Files	Coverage Δ
src/modules/helpers/index.ts	98.98% <100.00%> (ø)

... and 1 file with indirect coverage changes