[os-cloudflared] Correct UI token entry text field validation mask

[csedm]

Correct UI token entry text field validation mask to include equal signs which are standardly present in Cloudflare tunnel tokens

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Describe the problem

Valid cloudflared tunnel tokens from the dashboard cannot be entered under the current UI text field validation mask.

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Describe the proposed solution

Add the equal sign to the hash as a valid character, allowing valid tokens to be entered. Update validation error message to include the equal sign.

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Related issue

#5597

Additional notes
It's worth mentioning I'm not 100% positive this is the correct and complete fix since so it ought to be validated by someone who knows this project better than I do. It looks sufficiently correct to me based on examination of similar files on my own OPNsense system and successful testing of the fix.

[Monviech]

@insanityinside fyi

[insanityinside]

Will double check the validation logic, in case I've missed anything else.

[insanityinside]

I missed the = from the Base64 encoding validation for the token. Looks good to me, @csedm please bump the version in the Makefile to 1.2 before it gets merged.

[csedm]

Done, thank you!

[Monviech]

Merged, thanks :)