cache suffixes in resource tree

[wyfo]

ROS2 experiments shows that a lot of keyexprs shares common chunks, which can be quite big, for example:

• 0/pub_20/set_parameters/rcl_interfaces::srv::dds_::SetParameters_/RIHS01_56eed9a67e169f9cb6c1f987bc88f868c14a8fc9f743a263bc734c154015d7e0
• @ros2_lv/0/5639ab36ef9be8852b663e09962a618d/0/4/SS/%/%/pub_20/%pub_20%set_parameters/rcl_interfaces::srv::dds_::SetParameters_/RIHS01_56eed9a67e169f9cb6c1f987bc88f868c14a8fc9f743a263bc734c154015d7e0/:2:,1000:,:,:,,
• etc.

In order to reduce the memory consumption, this PR caches the chunks in the resource tree, using a kind of string interning. Also, small chunks like pub_20 are directly stored inlined in the bytes of the chunk pointer (small string optimization).

[codecov]

Codecov Report

Attention: Patch coverage is 70.27778% with 214 lines in your changes missing coverage. Please review.

Please upload report for BASE (main@4b035b7). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
zenoh/src/net/routing/hat/router/queries.rs	10.90%	49 Missing ⚠️
zenoh/src/net/routing/hat/router/pubsub.rs	18.51%	44 Missing ⚠️
zenoh/src/net/routing/hat/linkstate_peer/pubsub.rs	64.00%	18 Missing ⚠️
...enoh/src/net/routing/hat/linkstate_peer/queries.rs	67.34%	16 Missing ⚠️
zenoh/src/net/routing/hat/linkstate_peer/token.rs	73.07%	14 Missing ⚠️
zenoh/src/net/routing/hat/router/token.rs	75.86%	14 Missing ⚠️
zenoh/src/net/routing/hat/p2p_peer/token.rs	58.33%	10 Missing ⚠️
zenoh/src/net/routing/dispatcher/suffix.rs	93.91%	9 Missing ⚠️
zenoh/src/net/routing/hat/client/token.rs	50.00%	8 Missing ⚠️
zenoh/src/net/routing/hat/p2p_peer/pubsub.rs	61.90%	8 Missing ⚠️
... and 8 more

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1814   +/-   ##
=======================================
  Coverage        ?   71.01%           
=======================================
  Files           ?      361           
  Lines           ?    65293           
  Branches        ?        0           
=======================================
  Hits            ?    46366           
  Misses          ?    18927           
  Partials        ?        0           

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