Avoid some string allocations

[Henr1k80]

Prerequisites

• I have added steps to test this contribution in the description below

Description

Avoid allocating strings when spans can be used when:

• Parsing
• Concatenating values
• Splitting (here is also heap allocated an array to contain the strings)

This is archived by using spans from regex matches, trimming on spans & spans instead of sub-strings.

There is also

• count single chars with spans instead of 2 string replace operations, that allocates strings.
• removed some unneeded trim operations, that allocates a string, if trimming happens.

@AndyButland v17 version of #23399

[github-actions]

Hi there @Henr1k80, thank you for this contribution! 👍

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[AndyButland]

Thanks again @Henr1k80. Looks good, though I believe a regression has sneaked in here, so could you look at that before we merge please?

[AndyButland]

Thanks for the updates @Henr1k80 - looks good to me now.