This commit is a preparation for upcoming changes to
KeyChordSerialization for #7539 and #10203. It introduces several
string helpers to simplify key chord parsing and get rid of our implicit
dependency on locale sensitive functions, which are known to behave
erratically.
Additionally key chord serialization used to depend on iteration order
of a hashmap which caused different strings to be returned for the same
key chord. This commit fixes the iteration order and will always return
the same string.
## Validation Steps Performed
* Key bindings are correctly parsed ✔️
* Key bindings are correctly serialized ❔
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