Distributed TRC support

[okt-kostik]

TE allows to have TRC in the tests. This is really great.

Said that if one is developing a NIC and wants to track results that are specific to the NIC. W/o merging the results into the TRC of the test suite:

• it's very bad for merges
• it can't be upstreamed given that it might be private.

I suggest you support distributed TRC. Namely:

• TRC might be located in several places
• Places have priority
• If a result expectation is specified in high priority location - it overrides low priority
• it's possible to specify:

 359     <test name="mtu_tcp" type="script">
 360       <objective>Check that TCP packets of full MTU size are sent and processed correctly.</objective>
 361       <notes/>
 362       <iter result="PASSED">
 363         <arg name="env"/>
 364         <arg name="mtu">576</arg>
 365         <arg name="tx"/>
 366         <arg name="gso_on"/>
 367         <arg name="tso_on">FALSE</arg>
 368         <arg name="pkt_size"/>
 369         <arg name="sends_num"/>

something like:

<test name="mtu_tcp" type="script" override="true">

that will result in override of the entire subtree by the content in the file