Task 562/fix handling of duplicate signals

[Kostadin-Ivanov]

Updates done:

1. Fix handling of top_vss_tree_unique_node_names by setting more stable node key handling for better identification of repetitive nodes
2. Update handling of ttl_name so it can be used better for nodes property name definitions
3. Update handling of PREFERRED_NAME so to preserve node name casing and parent name casing, if needed, when human readable PREFERRED_NAME value is defined for the corresponding node
4. Update SAMM unit for Celsius and add a new SAMM unit for the VSS "ms" unit
5. Update string_helper to handle better CamelCase strings and split those for the more "human friendly" "split camel case strings"
6. Replace some hardcoded strings with corresponding SammCConcepts and SammConcepts constants

[erikbosch]

MoM:

• Please review

[erikbosch]

LGTM

[marnova]

LGTM too :)

[erikbosch]

MoM:

• D - Duplication of units also appeared some times ago
• E - unrelated
• Ok to merge