[typescript-axios] add config parameter to specify custom axios version

[dougkeen]

Fixes #16642

Creates a new configuration parameter for specifying axios version. This seems like a suitable "special case" to avoid a fully custom template just to bump the axios version, which is a common use case as security updates are made to the axios lib.

This has been end-to-end tested locally (generating a test client and validating that the axios version is changed as expected). I've also added unit tests.

cc: @TiFu @taxpon @sebastianhaas @kenisteward @Vrolijkx @macjohnny @topce @akehir @petejohansonxo @amakhrov @davidgamero @mkusaka

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[dforesman]

Non-blocking suggestion - a bit more detail on acceptable values could be helpful here, something like:

Value may be any valid NPM semver string that matches an existing version of axios.