Add const to string parameters

[ataffanel]

If a function does not modify its string input, it should be declared const so that the api user knows that the string will not be modified (it can be static) and to make the compiler check that we are not modifying the strings.

This PR adds const everywhere I could find it was needed.

[jonasdn]

Looks great!

Do we have all relevant gcc warnings enabled about breaking const qualification?

[ataffanel]

Do we have all relevant gcc warnings enabled about breaking const qualification?

Yes I just tested and trying to modify const strings end up with an error:

  CC    log.o
.//src/modules/src/log.c: In function 'logGetVarId':
.//src/modules/src/log.c:980:11: error: assignment of read-only location '*name'
  980 |   name[0] = 1;
      |           ^
.//src/modules/src/log.c: At top level:
cc1: error: unrecognized command line option '-Wno-stringop-overread' [-Werror]
cc1: all warnings being treated as errors
make[1]: *** [tools/make/targets.mk:27: log.o] Error 1