[typescript] fix issue with special characters

[mayrmax]

Fix issue where special characters such as @ get stripped in the abstract typescript options. This changes affects all typescript generators.

Fixes:

• [BUG][TypeScript Angular] Leading '@' stripped in field names #8155
• [BUG][typescript-angular] allow colons in TS interface property names #6810

@TiFu @taxpon @petejohansonxo @amakhrov

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[mayrmax]

Seems like this leaves the breaking @ in, maybe ^[^\w_$@]*|[^\w$] would work.

[mayrmax]

@sebastianhaas @kenisteward @Vrolijkx @macjohnny @topce @akehir

[amakhrov]

Thanks for your contribution!

A few thoughts:

• Could you please provide examples of the code generated before and after this change?
• Let's add some tests verifying the changed behavior
• I'm slightly concerned that with this change TS generators will generally produce uncompilable code, since models are generated without quoting. We probably need to update all templates to account for unsafe identifiers:

// before 
interface SomeModel {
  @unsafeName: string;
}

// after
interface SomeModel {
  '@unsafeName': string;
}